[David Dunlop]

Alastair.

The key is in the sleeve I think. It very likely locks the Boys Rifle into a secure travel position. From there it would move to an unlocked position allowing the Boys to be elevated for aiming purposes. It's final movement would be to back off enough from the mount assembly to allow the Boys to be removed entirely from the mount in the Scout Carrier and taken afield.

It would not surprise me at all if the Boys had little, or no, traverse capability in the unlocked firing mode. The German Hetzer self propelled artillery vehicles had minimal traverse ability. If significant traverse of the gun was necessary, the driver adjusted the position of the vehicle in coordination with the gunner to bring the main gun to bear on the target. A similar process would work with the driver and gunner in the Scout. Should the crew of the Scout encounter a target, I suspect it would likely be under circumstances where the engine is running and you have options if the situation gets too dynamic, so giving your carrier a bit of a wiggle would be no big deal.

David