Hi Akira
I agree, I think that was probaly for everyday access, i.e. nice weather, normal peacetime patrols, but I think when in bad weather or battle situations I think they would use the internal ladder in the foremast to climb up to the control platform then climb down to the director. On the Sambrook plans it is difficult to read as there is so much writing in such small areas. Geoff, if you look at the second detail plan showing the different deck levels there is a manhole on the starboard side of the upper rangefinder, almost underneath the rangefinder. Its got a written marker next to saying its a manhole and I can't see anything else it could go to other than the director platform. I still haven'd found any hard proof though...
But on a similar vessel, HMS New Zealand, the director is fitted in a similar position, I've attached this picture incase you can see anything that I can't.

Done a bit more planking on the quarterdeck, hopefully the planking will be finished next weekend.