Rudi - what did I tell you about all the MF lookalikes in Soho on Saturday evenings? Did you spot anyone with blue fluff in their turn-ups?
BA can be strict about carry-on luggage, particularly if flights are full. Heathrow isn't usually too bad for this, but try getting on to an overcrowded flight to Africa (mostly from Gatwick) - everyone tries taking at least ten pieces of hand luggage!
At one point in my student days I had to deceive the check-in/gate staff, because I was taking a bag containing over 200 cds and an expensive camera with loads of lenses, camera equipment, etc. The bag was heavy, but there was NO WAY I was going to check it in - the contents would never have made it to the other end safely. (Not to mention the amount of duty I would have had to pay on arrival) So the check-in staff, who were sympathetic, told me that I could take it through and check it in when I boarded - this got me past the man who wouldn't let me into the passengers-only area with the bag - and when I got to the plane the crew told me I could keep it with me.
Of course, when I arrived, I went sailing through the 'green' line! (Everything was eventually re-exported, so I feel no guilt...)