Nearest I've seen is 42mm ID with a 44.8mm OD with a wall thickness of 1.4mm. This can be easily honed out with a snug fitting flapper wheel. Or a quick skim out on a lathe.
Thanks. I'd hoped to get something that fitted without rework, but I think this would be my best bet. On the other hand, at over 40 quid delivered the scope may have to go without a sunshade. After all, the weather where I live isn't known for its sunshine !