I have a great, very durable, metal framed roll-aboard that I bought at LuggageWorksOnline. A lot of airline pilots in the U.S. use the same bag.
Not the lightest, but can take a real beating. Plus the company will refurbish the bag when it needs it (for a fee, of course).
The website is:
LuggageWorksOnline
Don't know about shipping to the U.K.