Andrew, to put my twopennath in, I agree with Grif. Mine is Gp4 square arch, and I don't have any trouble on the narrow lanes, which frankly I prefer as a driving experience, in fact to a point it helps as oncoming traffic seem to think that something the size and shape of a Stable door on edge is approaching them. I link below to a post I put on back in 2020, see post 81. (My wife now drives it quite often.)

Northern Drive-Out - Coast & Castles Run, Fri/Sat 7th/8th August 2020