A Little Further Info
Thanks for your responses thus far. On our return to the UK I contacted Easyjet by phone who immediately seemed to adopt a default position and deny everything. It was this that really got my back up. The crux of the matter is that they considered the flight to have been re-scheduled not cancelled. But a flight that has been moved to a different airport on a different day with a different flight number must surely be considered a replacement of a cancelled flight.
The a/c problem is something of a red herring as the Captain confirmed that it had been repaired and they were awaiting a replacement crew.
The solution to the problem was staffing not technical. Get a new crew and off we could have gone.
I have written to Eastjet and await their reply with some interest. Hopefully they will do the "right" thing and bring the matter to an end. However, being retired I have plenty of time to persue this as far as necessary should needs be.