Thanks John - that is an ED78 in the image, so I'm hoping that as the focus ring is behind the tripod foot it will be recessed further back and will work. I took a punt on the case for the ES80 series, and hoping that it will work. If it can be used as a stay on case, that'd be a win, but as long as it fits and provides some protection for travelling, I'll be happy enough.
I'll post some thoughts and photos when it arrives in case anyone is in a similar situation and struggling to find an alternative case.
Maybe I should just replace my Nikon scopes with Opticron equivalents at this point!