I dont think it's an English thing, I think he's gone with recency bias and decided in Fletcher because he was looking right at him when a decision had to be made, and allowed that to cloud his judgement. It absolutely should have been Miller that replaced Gilmour.
On the original 26 he probably looked at Mcginn, Christie, mctominay, Gilmour, Ferguson and mclean as the main group, with the first 3 lilely being the starters. I'm fine with more strikers, you need potential impact players in tournaments.
The squad has a fair mix of Scottish (at least 7), English, and abroad based players (Italy and Saudi at least, forgot where mckenna is playing), and also some relatively new call-ups in Curtis, Hyam and Fletcher, and while he has his favorites, i dont think that there's many legitimate shouts for guys that have been hard done by.
I'm not as down on Clarke as most, but my gripe with him is the way we play, less than who he selects.