It might not necessarily be British - I've had/seen a few 1970s/80s suncatchers from Danish house clearances with Bargeware-style decoration - some of them clearly painted by hobbyists. Glass suncatchers with screenprinted tourist designs and later, completely unrelated, hand-painted floral borders seems to have been a thing.
And, of course, cast glass suncatchers are far more common in other parts of northern Europe than in the UK.