Hi Kristina.
I don't think too many people grow Gal. plicatus 'Upcher' these days as it's a fairly ordinary-looking selection from plicatus with nothing really special to distinguish it from a lot of other plicatus. The last time I saw it was a small and dwindling clump in the garden at Foxgrove Nursery near Newbury (who specialise in snowdrops). And that was quite a few years ago.
From memory, I'd say your snowdrop looks okay to be Upcher, and I'm pretty sure Primrose Warburg would have had it labelled correctly.
Hope you're enjoying all the fantastic sunshine, especially amongst the snowdrops - a really bright sunny day can totally transform a snowdrop patch when the 'drops open up properly and put on a proper display.