I don't particularly follow F1 but out of curiosity how 'British' is Ferrari compared to Mercedes?
It has some UK connections and history.
The current Mercedes team is based in Brackley and employees a large number of UK people, but more Germans towards the top of the structure. Its also one third owned by Ineos (Jim Ratcliffe).
Merc used to be more of an engine supplier only, but bought out Brawn GP (Ross Brawn) in 2010. I guess with that transaction they got the workshops etc and all the staff of what was a UK team.
Ferrari by comparison are based only in Italy and whilst they have some UK people its mainly Italian workers.
So if you wanted to wave you're British flag for a team, Merc does edge it but its still not "British" British.
Pure British would be McLaren F1 in most peoples eyes, but they are majority owned by the sovereign wealth fund of Bahrain.
Even Aston Martin is partly owned by a Canadian (not sure if its majority or simply the largest) and Williams are owned by Dorilton Capital (USA).
These days with the cost of running an F1 team being what it is there's really not many people or institutions in the UK who have the financial resources to own outright.