What hotel was it?
I guess it’s down to the British hotel star grading system, which is very different to that in some other countries, especially those in the continental Europe or America.
I believe you were just unlucky, next time make sure you read guests’ commets on some travel websites, such as http://www.tripadvisor.com
There are also many decent hotels in the UK, most of them are modern. My rule of thumb: look for modern looking buildings if you are looking for a comfortable hotel, don’t look at the star rating… Most of the times it works just fine!