My parents in law have moved back to Spain from the UK, and would dearly love to receive BB, ITV etc (Sky Sports in an ideal world). The problem is they're in Galicia, so not a popular ex=pat destination, and they live in a flat so they can't have a satellite dish. Finally they are not computer savvy enough to watch some of the services online. Anyone got any idea if there's a cable provider in Spain through whom they could get such services ?

No official cable provider like ONO will provide these UK TV services. They are SPanish TV cable companies so will only buy the access rights for Spanish channels.
Only ones on "expat" areas that do rebroadcast cable systems.
Looking at he maps a 1.5 to 1.8m dish may suffice - you can get ITV1, C4 and Five and Sky SPorts 1,2,3 on a "small" - like 80cm -1m dish. But for the BBCs and ITV2,3,4 then a bigger dish wil be required.

Thanks for taking the time to reply. Unfortunately they can't get agreement from their neighbours to stick a dish on the roof.

We are in Galicia and we have a 1.8m dish. We had a smaller dish when we first moved here, but we lost the signal about 5.00pm.

And cable companies will vary between locations, most of Galicia, outside the citie,s do not have cable TV.