Thank you for your letter received in this department on the 15th November regarding the identification of a grenade.
This museums munitions collection contains two examples of the type of grenade shown in your sketch. They were given to the museum in 1946 by Lt Col M I Williams Ellis who had commanded the 1st Merioneth (North Wales) home guard and were designed by him for use by that unit, both as a practice grenade and an emergency high explosive grenade. We have no details of date of manufacture etc, but I would think that they date from the period shortly after the formation of this unit, before adequate supplies of proper grenades were available to the home guard. Our information does not include where the grenades were made or whether they were widely used among other home guard units in North Wales.
Used as a practice grenade they would contain a small amount of black powder, which was ignited by a short length of Bickford safety fuse, and when thrown would produce an explosion just strong enough to expel the wooden plug. The body could then be retrieved and refilled. As an HE grenade the gunpowder charge would be replaced by a larger amount of explosive and the same fusing method but attached to a detonator to initiate the main charge.
I hope this information will be of help to you.
Department of exhibits and firearms Imperial War Museum