1944 20 mm Quadruple mounted AA Gun ‘Polsten’

Built by the John Inglis Company in Canada for the effective defend against V1 flying bombs or “Doodle Bugs ” against Southern England but also used extensively to defend Antwerp

This Quadruple Mount Polsten AA Gun
This Quadruple Mount Polsten AA Gun is still in great condition. It is a trailer version produced by the John Inglis Company from Toronto Canada. John Inglis and Company was a Canadian manufacturing firm which made weapons for the United Kingdom and British Commonwealth military forces during the World War II.

The company reincorporated in 1913 as the John Inglis Company Limited.
During World War I, the company turned out thousands of shells and shell forgings, and more than 40 steam marine engines for freighters.

In 1937, the company was purchased by Major J. E. Hahn of Toronto, owner of British Canadian Engineering Limited, who took on the name John Inglis and Company.

In March 1938, the company won a contract with the British and Canadian governments to supply 5,000 Bren machine guns to Great Britain and 7,000 to Canada. Both countries shared the capital costs of creating a factory to produce them. Inglis started production in 1940, and the contracts were extended several times.

By 1943, they were producing 60% of the Bren machine guns destined for the British Commonwealth forces, and 30% of the British Army’s own requirements. In the same period the company also produced a large proportion of the Polsten 20 mm autocannon for the British Commonwealth, as well as the Browning Hi-Power (or High Power) pistol for both the Commonwealth nations and other Canadian allies (Note: primarily the Nationalist Chinese Army). They also produced the machinery for four Tribal-class destroyers.

This unit was, after it remained in service into the 1950s, acquired by a Dutch collector in Southern part of the Netherlands in the late nighties. It was one of a lot of ONLY 3 surviving units!

He fully restored it and made it functional again in 2014. Therefore, he also acquired the 4 missing 20 AA guns from a specialized supplier in the UK to complete the set.

In 2014 and 2015 the set was often towed it in parades (70^th Anniversary) and tours behind an GMC. Due to purchase of new projects the unit was sold to a Belgium collector.

 The AA Guns is still in very good condition.
Moreover, from this set are only a very few remaining examples available (as far as we know only 3 in Europe).

The AA gun will be delivered with its original canvas covers and in operational order however we mentioned that due to a non functional magnet the engine is currently not 100% running. UK and NL deactivation certificates available.

 Therefore, this unique unit will be a huge asset for a serious AA gun or vehicle related collection!

The Polsten machine gun is a 20mm weapon which has been designed primarily to fulfill an anti-aircraft role against low flying aircraft and pilotless planes.
It is similar in principle to the 20mm Oerlikon gun which was used by the Navy, and it fires the same High Explosive, Incendiary, Tracer and Armor-piercing ammunition. This makes it an extremely effective weapon when employed in the A.A. role.
In a secondary role it may be used with good effect against ground targets, e.g., soft skinned transport and lightly armored vehicles. There are several mountings on which the Polsten was used;
• No2 Universal mounting,
• Mk1 Haszaird-Baird mounting,
• 20 mm triple mounting,
• The Quadruple mounting
but it could be fitted, with slight modification to the firing gear, to other mountings on which the Oerlikon is normally carried.

Normally a spare barrel is provided with each gun. The barrel can be changed quickly and easily, and this was done frequently in order to reduce overheating and consequent barrel wear.
The Polsten magazine was normally a 30-round box type and was not really suitable for use on the quadruple mount so the 60 round Oerlikon Mk2 drum magazine was used.
This weighed 64 lb. (approx. 29 kg.) when filled with ammunition!

The Polsten machine gun had an unusual development history!
Its design originated in Poland. It was actually a Polish development of the 20 mm Oerlikon gun. The Polsten was designed to be simpler and much cheaper to build than the Oerlikon, without reducing effectiveness.

It was however transferred to the UK when the Germans invaded Poland in 1939.

The Polish team had been revising the basic Oerlikon gun with a view to simplifying the manufacture and reducing cost. The drawings were completed by a team of Polish, Czech and British designers. The design was then handed over to the British Sten Company (Pol(lish)-Sten) who produced the gun along with the John Inglis Company in Canada.

When compared to the Oerlikon cannon, which was made out of 250 parts, the Polsten was made out of 119 parts in combination with a smaller number of machining operations to turn them out without sacrificing the effectiveness or the reliability of the cannon.
Simplification of the design of the Polsten cannon made its production much cheaper.
In these days the cost of one Oerlikon cannon was about £350, while the cost of the Polsten was between £60 and £70.
The first 240 guns were produced at the end of 1943, and a further 13,548 during 1944.

In January 1944, the 21st Army Group decided that only 20 mm Polsten guns would be used as a standard light gun to simplify supply.

The Polsten was used as a substitute for the Oerlikon in the same roles, one of which was as an airborne unit anti-aircraft gun, used in Operation Market Garden. It was used on a wheeled mounting that could be towed behind a jeep.
The Quadruple Mount
Various double, triple and quadruple mounts were developed.

The design of the quadruple mounted Polsten was developed alongside the “Skink”, a modified M4A1 Grizzly medium tank which had a specially designed turret, using 4 Polsten Mk1 machine guns instead of the usual armament.

The purpose of the Skink was to provide protection for armored units and assault troops against low flying aircraft. The original program called for production of 135 complete skinks for the use of the Canadian Army and an additional 130 Skink turrets to meet British requirements.
Allied air supremacy in Northwest Europe eliminated the demand for this type of vehicle and on 23rd August 1944 the Dept of Munitions and Supply was advised by the National Defense that the program should be cancelled and only three tanks would be required. Of the three vehicles produced in Canada, one actually saw service in NWE during Feb and March 1945.
Although it wasn´t actually used in the A.A. role it was very effective in the ground role.

However, another threat loomed in 1944, that was the use of V1 flying bombs or “Doodle Bugs ” against Southern England by the Germans.

Conventional A.A. guns such as the 3.7´s and 40 mm Bofors were found to be inadequate to deal with the problem so a new A.A. gun was produced based on the Skink turret design.
The gun could be trailed into position anywhere quickly and then set up.

A team of loaders would keep the ammunition coming and the gunner would sit inside the armored turret and direct the fire using a joystick like an aircraft type control. The action was very fast, being hydraulically controlled, hydraulic power produced by a small Wisconsin single cylinder petrol engine in the rear of the turret.
The gunner had elevation control as well as traversing and could fire the guns as pairs or all at once!
A contract was placed for 1000 quad Polstens and they were all delivered.
The quadruple mount saw, next to defending the UK, service in Northwest Europe when it was used to defend Antwerp from the V1s.

By the end of 1944 / early 1945 a lorried version of the Quadruple Mount was also built using the turret and mounting from the trailer and installed it on the back of a CMP flatbed 3 tonner with a type 43 cab.

Polsten Guns, magazines and ammunition boxes were also made in Australia by General Motors Holden in South Australia’s Woodville and Beverley Plants during WW2.

They were used by the Australian Army onshore and on small boats. Several prototype gun mountings were also developed but did not see service.

Lot-0105-TT-Polsten-20mm-AA-Gun-Rev-2.0

Brochure: Lot 0105 T&T Polsten 20mm AA Gun Rev 2.0