Did BCN-LHR two Saturdays ago, arrived around 9:45am.
10 mins for check in and bag drop. One couple in front of us.
5 mins for fast track security, no queue.
10 minutes to go through passport control for non Schengen. There is no fast track here. Probably 20 people in the line but 5 desks open.
All very slick and stress free, longest line was for the lounge
Edit: allow 5 mins walking between each of the above, it’s a bit of a hike to the gates.