It's a bit ancient, stiff as a board and with an integrated forestay. I'd like not to have to buy another and so any ideas as to what it is, so that I can research parts and servicing tips would be great.
Don't know what it is, but if you don't manage to find out either have a look at Facnor SD drums. They look a bit similar, you can find lots of information for them so who knows..
I had something like that on the inner stay when I bought this boat. Bills showed the previous owner had fitted it second hand, think it was Colnbrook. Replaced it. Cut it up for scrap as unable to get the wire out of the drum assembly.
At the very least take it apart and check the forestay. Also, replace the shackle holding it to the deck fitting with something a bit more professional. The shackle is likely to distort and fail under load.