Rod,
Wow... quite a story.
One thing though -- the one carry on rule is something imposed by the UK government. The weight of that one carry-on, however, is something decided by individual airlines, and it pays to check it out in advance... as I discovered to my cost.
I have flown Virgin Atlantic several times between London and San Francisco, but on one occasion they decided to weigh my carry-on bag. Ooops -- full of Lenovo laptop, lenses and Canon bodies it healthily exceeded the carry-on limit for Economy class on Virgin (yes, I am a cheapskate). I really had not paid attention -- they are very clear on their website and elsewhere that there's a 6 kilo carry on limit for economy passengers. The alternative is to fly Upper Class, where the limit is officialy 8kg, but in practice you can take on board one bag of any weight you like, sir. I have done this and the whole experience is unbelievably great... but not on this particular trip.
BA changed its baggage policy in July this year, and it now has no restrictions on carry-on weight for any class. See
British Airways to change baggage policy - SmarterTravel.com
Again, at the end of the day, this is about checking up before booking and/or travelling. If I'd only entered "Virgin Atlantic hand baggage" into Google before booking I'd have known what to expect...
Mathew