British infantry operating a 2-Pounder.
Mk IX: Pre-war production with autofrettage barrel.
During the invasion of France the Low Countries, numerous 2-Pounders were captured and procured by the Germans. These were designated “PaK 192(e)” when captured from British troops and “PaK 154(b)” when captured from Belgians. 
In the Pacific and Far East theaters, the 2-Pounder remained a useful weapon against the much less developed Japanese armor. While it was retired from Europe and North Africa in 1942, the 2-Pounder continued to serve in the East for much longer. 
As fitted into fighting vehicles, the QF 2-Pounder was just over 2 meters in length and weighed 814kg. The Armor Piercing rounds were capable of penetrating 53mm of vertical armor at 500m. Although developed, this gun was never issued with a high explosive rounds, which limited its effectiveness in the field. 
2-Pounders mounted “portee” in North Africa.
In 1934 the War Office issued a request for the design of a 40mm Anti-Tank gun firing a 2-Pound shell. Vickers Armstrong began work on the design. The Army, however, did not bring the gun into use until 1938, by which point its 53mm penetration was struggling to keep up with advances in German armor  .
The 2-Pounder gun was mounted on various British military vehicles, mainly infantry tanks like the Valentine, Matilda, and early versions of the Churchill. A number of armored cars were equipped with 2-Pounder guns. Early cruiser tanks utilized the 2-Pounder as well.
The Ordnance QF 2-Pounder, often abbreviated to 2-Pdr, was a British designed and manufactured 1930’s era anti-tank gun.
Ordnance QF 2-pounder Production Information Technical Information Usage [Source] The Ordnance QF 2-Pounder, often abbreviated to 2-Pdr, was a British designed and manufactured 1930’s era Anti-Tank Gun.
*barrel only. Around 3m total with the three-legs platform carriage.
It has long been thought that the 2-Pounder gun was never equipped with High-Explosive (HE) shells, this is not the case however. HE was available to the 2-Pounder gun, but British military thinking was that firing Explosive Shells was the job of the Artillery. As such, towed 2-Pounder crews deployed by the Royal Artillery were equipped with HE ammunition, but Tanks, designed for infantry support such as the Matilda II, were not equipped with them.
The 2-pounder actually had two types of exploding shell produced for it, namely the 1934 – 1937 pattern APHE shell and the HE fragmentation shell. The shell weighed 1.87 Pounds and used the Hotchkiss base fuse Mark IV. The shell is a blunt-nosed serrated cylinder made of cast iron designed to strike the ground and pitch back into the air then explode, scattering fragments into enemy infantry and animals such as horses.
This shell was used by tanks of the BEF in France 1940 but although available in North Africa, was out of favor with crews preferring to stock their ammo racks with AP ammunition. However, anti-tank units always carried a supply for deterring infantry assaults against them.
The 1934 -1937 pattern APHE shell was produced before trials of the 2 Pounder gun took place but failed to meet the War Department’s specifications of being able to have a 70% (7 in 10) probability of penetrating 14mm. of vertical face hardened rolled homogeneous armor plate (Vickers “Vibrax” at a range of 500 yards.
In tests the Hotchkiss Mark.IV. base mounted fuse either fell out in the barrel during firing or fell out when the shell hit the test target despite the actual unexploded shell actually penetrating. In other instances, when the fuse stated in the shell would explode with no or partial penetration.
Because of this, the British Army elected to dispense with APHE ammunition from 1937 to the present day. Maximum penetration was 48mm. at 100 yards versus vertical FHRHA as live APHE and 59mm. at 100 yards versus vertical FHRHA fired inert/unfilled. 562,000 were produced between 1934 and 1937, none were fired in combat or even issued. Instead, stocks were used up on firing ranges in the UK for training and issued to home defense anti-tank units during 1940 after Dunkirk.
Information Provided by A. Reid, a former employee of The Tank Museum, Bovington
From 1935, the Ordnance QF 2-pounder was the staple Anti-Tank weapon used by the British Army, throughout the Empire. It only started to be replaced in 1942 as the 6-Pounder became available. However, its history was unusual for the time. It began as a specially designed gun for a tank, the Cruiser Mk.I, and as such, had to be compact, light, and fast to reload. At a time of budgetary cuts, the Director of Artillery chose it in 1934 also as the main AT gun for the infantry, mainly for standardization purposes. The three-legged mount construction was attributed to Woolwich Arsenal.
The standard 1939 2-pounder was the main infantry antitank weapon in service with the BEF in may-june 1940.
A 2 Pounder Anti-tank Gun Carrier (Universal Carrier) used by Australian forces in North Africa, 1941.
Chevrolet 30 CWT (WA/WB) 2pdr portee, the same type used by the LRDG in North Africa. This was a widespread solution, also declined on the Morris 15 cwt truck, CMP Ford F30 or Chevrolet C30, until the US-supplied lend-lease M10 tank hunter made them obsolete.
A British Army illustration of the 2 Pounder gun.
A Royal Artillery towed 2 Pounder gun, in service in North Africa. Source: – militaryfactory.com
Vickers won the contract for Ordnance QF 2-pounder Mark IX on Carriage Mark I, and a few prototypes were assembled and tested in 1936-37. The carriage was innovative, with a combination of small road wheels and legs, one of which, at the rear was also used as a towing tail, and the two on the front, shorter, were folded up for transport. When deployed, the wheels were lifted up and the three legs platform formed a strong support on all types of grounds, also allowing the mount a 360 degree traverse.
A second Mk.II carriage, simplified for mass production, included fully removable road wheels. Both the caliber and rate of fire of the 2-Pdr (a 40mm caliber) outperformed the German Pak 36 and similar 37mm guns in foreign armies. However, it was bigger, taller, heavier and thus easier to hit and slower to deploy. Also no HE round was never provisioned for it, despite such round was studied in 1940 but never materialized int production.
The Ordnance 2 Pounder found itself the only AT gun of the British army from 1939 to 1942 at least, when the 6-Pdr was introduced on the frontline. It saw action for most of the war in many theaters of operations with the Commonwealth armies, in France, Italy, Norway, North Africa, Eastern Africa, India, the Eastern Indies, and New guinea, not only as a standard infantry AT gun, but mounted on a variety of vehicles.
However in North Africa against up-armoured Panzer III and IV it proved useless but only at short range on vulnerable spots, and the situation would come to worsen over time. However, it was found adequate on the southern Pacific and eastern Indies against weekly protected Japanese tanks. Whoolwich’s only began to replace it by the spring of 1942. Both the range and efficiency of the ammunition used were improved in the meantime.
One improvement made to the gun was the adoption of the Little John Adapter on 2-Pounder Tank Guns. This adapter worked on the Squeeze Bore principal and fired a special APCNR (Armor-Piercing Composite Non-Rigid) high-velocity shell. It almost doubled the armor piercing capability of the weapon and would see service until the end of the war on vehicles such as the Daimler Armored Car.
*Using Littlejohn adaptator
The 2-pdr on Wikipedia
Osprey Publishing, New vanguard #98, British Anti-Tank Artillery 1939-45
Ordance QF 2 Pounder By David.B Post date Standard AT gun – UK. About 12,000 built 1936-44. The main British Antitank gun From 1935, the Ordnance QF 2-pounder was the staple