4.2" Mortar in British service late 1942

4.2” mortars - YouTube

Various examples. Albeit I think mostly re. the US/ i.e.



"A 4.2" mortar fires high explosive and phosphorus shells which explode on targets. Transportation of mortar and ammunition in large truck (10 men-10 rounds) is compared with that of a jeep towing a trailer bearing a mortar and ammunition (2 jeeps-6 men-48 rounds). Jeep and trailer units are tested at various speeds and on all types of terrain, fire mortars from barge landing craft as an island is approached, drive off barge, and are freed from ditches and other obstacles by their crews. Date: ca. 1939 - ca. 1945 Creators: Department of Defense. Department of the Army. Office of the Chief Signal Officer. 9/18/1947-2/28/1964 (Most Recent) From: Series: Film Bulletins, ca. 1939 1860 - ca. 1945 1985 Record Group 111: Records of the Office of the Chief Signal Officer, 1860 - 1985 localIdentifier: 111-FB-46 naId: 24456"

Saw this too in the 24th L Wardiary...

"23/11/43 Selected Officers of the Regiment attended a lecture on “Battle Intelligence” given by Lieut.Col.Ewart at HQ, 8 Corps.

2/Lts.F.B.Creamer, A.H.Wade and G.M.Elliott were attached to 165 OCTU, Dunbar.

Selected Officers of the Regiment attended a demonstration of the use of 4.2” mortars at Wheeldale."

From IWM / wiki... ML 4.2-inch mortar - Wikipedia

 

According to Hogg the British 4.2 inch Mk 1 was designed after studying the older US 4.2 inch mortar. The latter was originally intended to dump large quantities of gas as fast as possible over an area and so pin point accuracy and target spotting may not have been so relevant. By the time the British 4.2 was entering service the US 4.2 was in the process of replacement by the 81mm which was a licence built version of a Brandt mortar.
It is probable that a few US 4.2s were acquired by Britain when the British 4.2 was under development

 

One thing I remember reading about the 4.2" mortar is that they couldn't be used at anything approaching close range, because the burst area of the shell was ridiculously large, something like 400+ yards in diameter.

 

Well they were designed for chemical warfare

 

The British smoothbore 4.2" mortar was developed from the WW1 Stokes MkI 4" mortar (similar to the 3" mortar which was developed from the 3" Stokes) which was mainly used as a chemical weapons thrower.
4-inch Stokes Mortar by Dustin Holmes, on Flickr

The US M2 4.2" mortar was also developed from the Stokes 4" mortar but with the addition of rifling it became the M1 4.2" chemical mortar. Newer stronger barrels and High Explosive bombs led to the M2 mortar.

 

True but somewhat incomplete. The US 4.2 mortar owed its existence to the development of a system that allowed stocks of smooth bore chemical ammunition made for the American copy of the Stokes 4 inch to be fired from a rifled mortar. This was achieved by fitting a deformable plate to the base of the rounds which was deformed by the explosion of the propellant to fit into the rifling lands. Much in the same fashion as the old Mine balls of the 1860s.
Britain had never really taken to the Stokes 4 inch preferring to use the Livens Projector to deliver chemical weapons in quantity and this was still in production in 1939. The military top brass decided that this was a wee bit old fashioned and primitive and in 1942 demanded something more modern - and quickly. It was decided to produce something on the lines of the US 4.2 but without the rifling - producing new calibre smoke rounds was quicker. So although both weapons have the Sokes 4 inch in their family tree the descent was not as direct as you suggest.

 

A few manuals relating to the 4.2" mortar - if its any use I'm sure I can dig them out and scan some odds and ends