The LAG, officially named the "Respirator, Anti-Gas, Light", was a mask which helped pave the way for other Lightweight Respirators of the time. After the war, the 17 designations of Light Anti-Gas Respirator were dropped at the point of the LAG Mk. V mask. By the early 50s, a new model was created known as the Mk. 6 and later, in 1957, the Mk. 7. These two Respirators Served the British Armed Forces up-to and beyond the transition of Service Respirator No. 6. The latest military issued example of one of these Light Anti-Gas Respirators is dated 1969, implying service continued until roughly 1970 with confirmation from footage of the Aden Emergency in 1967.

If you use this information, please credit the user/collector Baroque4Days. This information was unknown until B4D's re-write.

Design Edit

Light Anti-Gas Respirators Mk. 6 and 7 saw fewer changes to their design during their time in service and also avoided the excessive naming conventions of the Second World War. Whilst the wartime Light, Anti-Gas respirators had a total of five primary designations and 17 total designations, Post-War Mk. 6 and 7 Respirators have but two primary designations and a few niche variants.

Breakdown of the Components Edit

Light Anti-Gas Respirators Mk. 6 and 7 feature a lot of components heavily based on WWII components, all of which retain the same name.

L3 (L3-4) Mask: Edit

Please note: It is uncertain whether the "4" marked under the L3 designation is, in fact, part of the designation. However, as the Post-War L3 masks vary from the wartime L3 masks, for the time being, I will be referring to them as L3-4 masks but please note that this IS NOT backed by documentation. For now, my assumption is that this was essentially the 4th variant of the L3 mask (faceblank), making the original wartime L3 effectively the L3-1. Again, this is purely speculation and is NOT backed by documentation. Once the lockdown finishes, I will be able to acquire the document which will give us the correct name. Thank you for your understanding.

- Baroque4Days

The mask, otherwise known as the faceblank, is the central component of the mask, the rubber mask itself. The L3 faceblank was initially introduced in 1944 however, comparatively, the L3-4 mask has been improved slightly. The L3-4 mask is very flexible yet not too thin with a comfortable and secure feel.

The mask is significantly lighter than the common L1 and L2 masks of the war yet are heavier than that of the Canadian C3's "C-1" mask. Compared to the L3 mask of the war, the L3-4 prefers a more flexible quality to the more-so solid feel of the L3 wartime mask used on the Mk. IV and V LAGs. This is likely due to changes in the rubber blend used.

The L3-4 can be identified by its flat nose, as opposed to masks which featured a bossed triangle shape at the same point. Aside from this and the general flexibility, the L3-4 mask is cut the thinnest of all British Light-type masks, including the wartime L3. The final way to identify this mask, as with all other British and Canadian masks, is to look for the designation inside the mask where the nose would lie. The designation should read L3 with the number 4 written below and a horizontal line between the two parts of the designation.

The L3-4 mask actually varies a little depending on the size of the mask. There are actually two differences between a Normal and Small sized L3-4 mask. Firstly, the small mask includes both a slight extension to the support fabric for the nose area, reaching up onto the two support beams. The second difference is that the small mask includes a lip at the point of the chin. It is unclear how these modifications helped but it can only be assumed that the lip was there to raise the chin higher without having to modify the overall size of the mask quite as much. However, do note that the size difference between a small and normal mask is significantly different, this modification was mostly likely an additional supportive measure.

L3 Holder, Valve: Edit

L3 Valve Holder (Post-War)

L3 Valve Holder (Post-War)

The L3 Valve Holder used following the war is identical to the less common type used in the war which uses the slightly improved diaphragm unit with a grilled-roof to help better protect the diaphragm sheet itself. Whilst this was, of course, a major improvement, it was, as said, something that was used already during the war, ony by this point it was decided to adopt this type, the L2 Mk. I Diaphragm, completely.

Unlike the wartime examples, the post-war L3 Valve Holders seem to have some more markings. For example, printed across the circumference of both grey and black painted versions is the designation No. 5 Mk 1, which one can only assume is either the designation of the front plate or, perhaps, a new designation for the Valve Holder instead of L3.

Most metal components are created by a company known as LSL, who have been known to make eyepieces on Post-War Light AG Respirators as well and, sometimes, by the company P Cow & Co. This company was tasked with creating 27K L3 masks during the war and nothing else but, despite this, they were clearly re-contracted to help with the efforts to mass issue the Mk. 6 LAGR.

No. 4 Mk. 2 Harness: Edit

No. 4 Mk

No. 4 Mk. II Harness

The final wartime component to be upgraded, or rather downgraded, was the head-harness. During the early days of the Mk. IV GS Respirator, the harness in use was known as the No. 4 Mk. II and was later replaced with the better-known No. 4 Mk. 3 with a rubberised head-pad and weaved straps. Following the war, we reverted to the No. 4 Mk. II design and merely changed the "II" to a "2". This harness was, of course, the predecessor of the WWII LAG's L2 harness and features a canvas hexagon connected to the 6 point head harness with adjustable straps. The difference seems to be the quality of material used on the straps. The black elasticated fabric used with the Post-War No. 4 Mk. 2 harnesses is the same material that would be used on S6 NBC Respirator. When compared to the older L2 harnesses, the newer material seems to have a much better service life. Whilst some 1944 made L2 harnesses are crumbling, No. 4 Mk. 2s made a mere 8 years later are in extremely good condition. The long and short of it is, we had a good thing going in the late 20s, we ruined it in the 30s, made cheap "light" versions of these two harnesses for the wartime LAGs and finally decided that nothing had improved since the 20s and we ought to just revert to the 20s design with slightly better quality straps.

Late No. 4 Mk

1964 Upgraded Harness

Around 1964, the remaining Light Anti-Gas Respirators in service, regardless of whether they were an Mk. 6 or 7, were fitted with unnamed, OD Green head harnesses which seem mostly identical to the 50s No. 4 Mk. 2 aside from the strap and canvas head-pad colour. This replacement appears to have only occurred if the original No. 4 Mk. 2 harness was damaged, as implied by a 1956 made and 1969 issued LAG Mk. 7 which retained it's undamaged No. 4 Mk. 2 black harness. This newer design better matched the straps of Service Respirator No. 6, the mask which was, by this point, the primary Service Respirator for Britain. These later harnesses seem to bear little difference in quality and were likely created from accessible materials to replace any worn head-harnesses during the transitionary period or to keep for war-stock.

The earliest and latest found dates of these green harnesses are 1963 and 1965.

Kit Contents & Progression Edit

Since WWII, the Light Anti-Gas kit saw numerous changes but ultimately remained the same in principle. Following the war, one standard kit was used though some variations have been found to have occurred around the 1956/7 mark with the introduction of the LAG Mk. 7.

1952 Pattern Kit: Edit

Item Designation
Respirator Respirator, Anti-Gas, Light Mk. 6
Container Light Mk. 3
Carrier Light II - Standard
Ointment, Anti-Gas No. 6 "Tropical & Temperate"
Outfit, Anti-Dimming Mk. VII
Eyeshields, Anti-Gas Mk. III

1957 Pattern Kit: Edit

Item Designation
Respirator Respirator, Anti-Gas, Light Mk. 7
Container Light Mk. 3
Carrier Light II - Dark Green (likely also the standard)
Ointment, Anti-Gas No. 6 "Tropical & Temperate"
Outfit, Anti-Dimming Mk. VII
Eyeshields, Anti-Gas Mk. III

1960s + Pattern Kit: Edit

Item Designation
Respirator Respirator, Anti-Gas, Light Mk. 6 or 7
Container Light Mk. 3
Carrier Light II - Standard
Ointment, Anti-Gas No. 6 "Tropical & Temperate"
Outfit, Anti-Dimming Mk. VII
Eyeshields, Anti-Gas Mk. III

Comparison between the Mk. 6 & 7 Edit

Respirators, Anti-Gas, Light served seemingly interchangeably by the 60s due to the fact that there were very few differences between the models. However, some minor points were changed between the two models which set them apart from each other.

Similarities between the Mk. 6 & 7 Edit

Light Anti-Gas Respirators Mk

Mk. 6 & 7 Compared (Exterior)

Both models share a lot of components in common. Firstly, the L3 Valve Holder that was used on WWII Masks designated Mk. III and Mk. V continued service with both Mk. 6 and 7 Respirators. The only difference was that a speech amplifying device was screwed into the inside of the bossed centre.

The Mk. 6 and 7 Respirators also shared the same head-harnesses. Both originally used No. 4 Mk. II harnesses, likely upgraded from the original wartime harnesses bearing the same designation. Into the 1960s, both masks received upgraded green-coloured harnesses with no clear designation.

Differences between the Mk. 6 & 7 Edit

Light Anti-Gas Respirators Mk

Mk. 6 & 7 Compared (Interior) - Note that the Mk. 7 example is a size small, hence the chin-lip

Whilst both models shared a lot in common, there were a few key upgrades to the Mk. 6 Light Anti-Gas Respirator when designing the Mk. 7. Whilst both Respirators use the mask designated L3-4 (potentially an upgrade to the 1944 L3 mask seen on LAG Mk. IVs and Vs), the L3-4 mask used on the Mk. 7 LAG actually includes two differences.

The most notable difference between the two is the fact that the Mk. 7s were all painted black. Some Mk. 6 masks have been seen with black painted parts but only the true Mk. 7s use all black parts. The other difference between these two respirators is in the lenses. Mk. 6 Respirators use Mk. III Lenses whilst the 1956/7 made Mk. 7 Respirators use Mk. IV lenses. The difference between the two is that the Mk. IIIs, used from the Mk. IV General Service Respirator, all through the war until the Light Anti-Gas Mk. 6, use threads. This means that the two parts can easily be unscrewed to allow for easier lens replacement. The Mk. IV lenses do not feature threads and would likely have either been opened with a special tool or perhaps just replaced entirely.

Differences between the L3 mask during WWII and Post-War Edit

Whilst the L3-4 mask of Post-War was a unique design, the L3 mask platform was initially introduced in 1944 with the Mk. IV and V Light Anti-Gas Respirators. Telling the WWII Period L3 Mask apart from the Post-War "L3-4" can be difficult to the untrained eye due to the shapes described in technical manuals being identical, such as the additional horizontal support beam, support fabric between the lenses, the use of single letter-size designations, etc. However, there are some minor differences which can be used to identify between the two (also see the image for colour references below). The differences are as follows:

LAG L3 Faceblank WWII and Post-War Differences

See bulletpoints associated with the 3 colours in the picture

  • Red: The wartime L3 simply says "L3" between the lenses whereas the post-war variants are labelled "L3" with a line underneath and a "4" beneath the line.
  • Blue: The Support fabric on wartime L3 masks is slightly visible and is completely coated on post-war masks.
  • Green: The two vertical support beams were much more "squared" in the wartime mask and were moulded much smoother, almost rounded, post-war.
  • Aside from this, there is a clear difference in rubber quality with the wartime masks feeling somewhat more firm, however, this could differ between manufacturer. Also, bear in mind that the above example is synthetic rubber.
  • Underneath the chin, wartime masks should be marked "Mk. IV", "Mk. 4", "Mk. V" or "Mk. 5" whereas post-war masks will be marked "GD" + a date and then either the designation "Mk. 6 or Mk. 7".

Early Industrial 40mm Variants (assumed BNFL) Edit

R3 - GasMasksUK

From the collection of Danny McGurk

Some examples of both Mk. 6 and 7 Light Anti-Gas Respirators have had 60 to 40mm adapters permanently glued into the 60mm filter port. These adapters differ from the commonly available ones used by the Danish and were British made. They were fitted with a Leyland & Birmingham D10 "Vapour & Particle" 40mm canister which was different from the standard canisters issued with the S6 or Light Mk. 7 Respirators. These filters are black and feature ribbing on the base.

Here is an example from the collection of GasMasksUK:

Due to the nature of the canister, and the commercial markings from L&B Rubber, it would seem that this was little more than a civilian or industrial variant created from surplus stock.

1980s - 90s 40mm BNFL Variants Edit

British Nuclear Fuels Ltd Mk

British Nuclear Fuels p.l.c or Ltd, now known as Sellafield Ltd, were/are a government-owned company specialising in, as the name implies, nuclear fuels and energy. This company was somehow involved with the operations at the Windscale, now Sellafield, Nuclear Plant, notorious for its leak and the careless attitude taken towards the cleanup.

This company often gifts the Science Museums Group with interesting items, including the fairly well known C7 General Civilian Respirator variant featuring a PS10 Canister marked with a white tape band. Such is life, the company also seemed to do this with Mk. 7 Light Anti-Gas Respirators as seen in the main picture for this section. This mask is named by the Museum Group as the "Mark 7 Face Mask" and so, it can be assumed that there was likely no change in designation, just configuration. However, it is unclear whether or not these PS10 Canisters do, in fact, differ from the standard type. It could well be a particle based filter to prevent against nuclear threats. Do note that these respirators will always be seen with BNFL's trademark white electrical tape.

Though only one example has been found of this Respirator on the War Relics Forums, I am going to be hunting down an example or, perhaps, recreating one to provide more info around the subject.

Other Known Variants of the Mk. 6 & 7 LAGs Edit

The Light Mk. 6 and 7 respirators differ in numerous ways, however, they differ further due to the many variants which were created from these two respirators.

Firstly, some Mk. 6 Light Anti-Gas Respirators feature black painted valve holders. These seem to still be designated Mk. 6 and may have been the result of spare parts from the Mk. 7s being used on new production Mk. 6s. This type of Mk. 6 is fairly common and seems to hold no real advantage over the typical.

Nuclear 1950s LAG Mk

Nuclear school - HMAS Penguin Naval Base, Sydney - November, 1961

Atomic Test Variant (Forehead Container) Edit

Aside from these minor variants, as discussed earlier, the Mk. 6 and 7 Respirators both received harness replacements in the 1960s during the SR6 transition period. These were still designated Mk. 6 and 7. The final variant, and the variant which seems to be the most interesting to a lot of collectors, is a variant of the Mk. 6 & 7 Respirators which featured a forehead-mounted filter port. These respirators are known to have been used by various scientific groups with the filter commonly seen in Porton Down photographs. The best-known example of where these respirators were used was in Australian Nuclear Tests, most notably during Operations Buffalo, Antler and Grapple at Maralinga and Christmas Island and some further testing beyond into the 1960s. Footage from Baroque4Days Anti-Gas Equipment:

GasMaskUK Mk

From the collection of Danny McGurk

Windscale (Sellafield) Nuclear Plant (Hosed Variant) Edit

Photographed due to the 1957 fire at the Windscale, now Sellafield, Nuclear plant, examples of the Light Anti-Gas Respirator Mk. 6 can be seen worn by seven workers at the power plant. These Respirators have also been seen in a few collections with the only complete kit belonging to a YouTuber known as planes124.

This respirator, pictured here in this section, featured a screw-in hose which connected to a large filter designated "Type D/8/42" and was designed to filter toxic and radioactive dust as well as a fairly long list of gasses. This Respirator was packaged in a haversack which seemed to be designated "ON/AA/B/1018".

Windscale lag bag from planes124's video

From the collection and video of planes124

It is unclear whether the designation of the haversack is accurate however, this is the only marking found at the point where a designation would typically be written. As photographed, it is possible that the carrier was merely called the S 167, however, this would not match up to typical practice of the British during this time period.

Hosed Variant Mk. 6 LAGs in use at the Windscale Nuclear Site

The kit included with this Respirator consisted of a standard tin of Mk. 7 Outfit, Anti-Dimming, a pair of what look like either gloves or boot coverings, the haversack and, of course, the respirator facepiece with the filter attached. The facepiece, as was typical with all variants, was still merely marked with the designation Mk. 6.

The hose of this respirator appears to vary a little in manufacture from the few examples that have been discovered by collectors. For example, the pictured example from McGurk's collection features a fully flat circular piece which screws into the facepiece, however, another example appears to have a very slight embossed rectangle, spanning the diameter. The hose and container attachment, as well as the container itself, all appear uniform.

References Edit

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