See the first items in the range at:
https://www.johnsimons.co.uk/john-simons-x-paul-weller-1/
I've just had a quick look, and they seem to have all of the details. Is this the start of a wider range?
Don't think I can get on board with a that short, square hem on a long-sleeve shirt. In some of the photos, the collars also looks a little off-balance to my eyes. Nice checks though, and can see will appeal to many.
As well as being short and square of hem, they look like a very trim fit too. I suppose they're aimed more at the Weller/mod end of the market, which will hopefully bring in some extra cash for JS in these tricky times. The Stewart check looks nice, and you can't go wrong with a Blackwatch, but overall, not really for me.
Still shuddering at the state of Weller's hair...
If it's one of the sought after brands (Sherman, Brutus, Jon Wood and maybe some others I can't recall) and it's from the 60s or 70s then I expect you would get a lot for it.
(As the 'it' in question is a hypothetical shirt then that's not really much use to anyone but whatever.)