One can only guess as to how the trooper must have felt with this stimulus. It must have been interesting particularly if the trooper was in water or sweating. The 1944 edition of the pamphlet includes photos of the actual mount and how it is attached to both the M1928 and Ml Thompson.
Presumably the spotlight would have been only used by "special" troops or commandos. So the next time you see an MP5 with a flashlight attachment on TV with police or special troops, THANK THE BRITISH.