Thanks Paul, I guess if it lasts that long it is hardly worth adding a second one "just in case" The worse that can happen is no coffee for a couple of hours! OK, that is serious... but not life or death :)
OK, I have photos! It's clearly a blue 15kg Butane bottle, there is room for a second but I think I'll stick with one (see above). The locker needs cleaning up and if there is a vent checking and unblocking if needed. Once tidied and cleaned the storage space will be useful.
My only question now that remains is I couldn't see how that connecter works, I'd be grateful for any advice on how that works please.