Travelled Prestwick/Gerona return last week and seems there is no common policy re hand baggage.
On outward trip, an airport employee was at the entrance to seurity with a set of scales and was weighing hand baggage and enforcing the 10kg rule. A party of 4 ladies in front of us had a couple of cases slightly over and were told they would have to check-in their luggage. In the end, they had a mad scramble about on the terminal floor swapping stuff from one suitcase to another.
Coming home at Gerona there was absolutely no check by airport staff regarding weight and by the look of the size of some people's cases, there was no way they would be under 10kg. Some of them were enormous. Again there was no checks by cabin crew on boarding the aircraft.
Flight was nowhere near full, so this might have been a factor in lack of interest, although it was same situation with all flights leaving Gerona.