Id say from it's mouth and general shape that it's an F1, I could be wrong though as I tend to avoid places with them so don't see them often. I've caught what are supposedly F1 that have looked quite carpy and others quite crucian like so I'm not sure if it's quite a wide ranging definition or if there are distinct types of hybrids.
I used to fish a lake in Hampshire that had a small head of crucians and a large amount of carp including commons, and we would catch fish that looked exactly like commons, but the barbules were either tiny barely formed ones, or non existent. We caught a few that looked more like a crucian, but bigger and with tiny barbules ,and some that looked like F1s, but they weren't a thing in the mid 80s. Someone tried to claim the club Crucian trophy with one of the crucian looking ones , and doing a scale count of the fish from the photo showed it was some kind of hybrid.
Interesting views. My initial thought was a common but then the mouth and almost triangular shape of the fish talked me into F1. As I said originally I’ve caught supposed F1 that have looked mostly carp and mostly crucian so I’ve never been too sure what they are supposed to look like.
I'd say it's a common. We have some Carp in the clubs waters that look the same, even down to the tail colouring that are hitting the 17lb mark and some of those have no barbules. F1's don't go to that sort of size.