I believe that longthorne build their guns entirely in the uk. Including their own barrels machined from billet. I don't know much more about them but they have a website which may be worth a look. (don't know how to post links sorry)
Can't say I'm the 'new' webley's biggest fan but their 2000 sxs looks decent enough. one thing I do like about it is the Deeley and Edge fore end fastener . It looks nice, at least they're trying.
Maybe one day when this over and under 'fad' has passed, we may see some fine British gun makers appearing once more.
P.s. I don't dislike o/u guns. Just believe the old saying that...
'if god had meant for us to shoot them, he'd have made us all with one eye above the other ! '
