FWIW IMHO the OP was unlucky to be checked but slightly over the limit - I'd have been miffed as well.

As it happens after 25 happy years of business travel on BA I had the pleasure (?!) of my first Ryanair return this week - yes they are ruthless on hand luggage but boy can they turn round a plan fast. At STN they announced boarding before the plane was even at the gate and 25 mins later we pushed back! Everything else was attrocious and no I didn't want to buy a scratch card / can of red bull / copy of Hello....

so whilst I'll be glad to be back at T5 next week maybe there is a thing or two for BA to learn about consistentcy on hand baggage