Hi all, some answers to these questions.
There were just three LCT (CB) assigned to the British beaches on D-Day, two on JUNO and one on SWORD. These carried the six Fireflies of 259 Corps Delivery Squadron, manned by crews drawn from 2 CAB and 27th Armoured Brigade.
The LCT (CB) at SWORD was LCT 2337, which was given the plan serial number 548. It was part of Group II, Assault Group S3 and was manned by personnel of the 100th LCT Flotilla, RN.
The two LCT (CB) at JUNO were LCT 2338 (serial number 1420) (10 CAR-manned) in Group J.322 (9th Brigade Group), manned by 106th LCT Flotilla, RN and LCT 2041 (6 CAR-manned) in Group J.312 (7th Brigade Group), manned by 105th LCT Flotilla, RN.
There was no actual difference between LCT (A), (HE) or (CB), all were basic LCT 5 with armored conning towers and a raised ramp allowing vehicles to fire over the bows during the run in. On the British beaches LCT (A) and (HE) were loaded with Centaurs and Sherman OP of the Royal Marine Armoured Support Group (1st and 2nd Regiment and 5th Independant Battery). The difference between the (A) and the (HE) was that the (HE) also carried the explosives for the RE and RN LCOCU to use in clearing the tidal obstacles (in other words the designation (HE) was a warning
).
BTW, LCT (A), (HE) and (CB) were
not utilized for the AVRE of the Assault Squadrons, RE. Those were brought in on standard LCT 5 of other LCT flotillas, but were grouped with the same waves as the LCT (A) Flotillas, which appears to be the source of confusion on that point.
On the American beaches the LCT (A) and (HE) were loaded with the wading tanks of the DD tank battalions (two each) as well as tankdozers for obstacle clearance (one each). Again the designation (HE) simply meant that it was one loaded with the explosives carried for the Special Engineer Task Force.
Curiously however, in one of the various D-Day studies prepared by the army and navy staffs in 1945 a reference is made to LCT (CB) at the American beaches! (Part III, Naval Forces, Strength and Casualty Special Study for Gen Morgan and Gale, 6 February 1945, NARA RG 338, ETO Secretary Genaeral Staff, Statiistics Section, Historical and Statistical Reports, 1944-45, Box #2.) This counts three LCT (CB) in the Eastern Task Force and two in the Western Task Force. Unfortunately, I have been unable to identify them in any of the task force reports for the Western Task Force, so they may be a mirage.
(Actually, since the Americans did not have two Fireflies to put in them, they were simply subsumed as LCT (A) and (HE) in the American plans).
Sources for the foregoing are:
ADM 179/391, 458, 504, 505, 506, and 516 and ADM 199/1558, 1559, and 1561
Hope this is of interest.