A puzzle, as the position of the winch would seem to rule out ammo trollies for any nearby gun emplacement and the boom wires would lead across the tracks to that bollard?

Yes, the bollard is probably the stump of the old mast that supported the boom. I shdve taken a close up, will pop out next week.

Of course the track and the room may pre-date the boom and by the time the boom was in use the tracks may have been disused for many years. My memory always has a metal sliding door across the entrance to the boom room.

I was just waiting to see who'd spot that first, Wilson. Discussion now continued under Winch Room (outside view).