marriedinwhite - I too have had an incident in the Waitrose in Putney!
I was queuing for the basket-only tills - 2 pairs of tills and one central queue as you probably know. It was a long queue - about a dozen people waiting - and it would have been a little tricky to miss it.
I was about halfway down the queue and there were two women in front of me with babies in buggies. I was heavily, visibly pregnant at the time. A man, probably in his 60s, wandered down from the back of the queue and re-inserted himself into the queue in front of the first of the two buggy women. The three of us looked at each other with our mouths open and then I turned round to look at the people behind me, all of whom were making "what the actual fuck?" gestures.
The first lady tapped him on the shoulder and said "Excuse me. You appear to have jumped the queue." At which point he went absolutely ballistic - in a terribly posh way - and started shouting "Oh, I'm terribly sorry, I'm not as important as you because I'm not a mother, because I don't have a baby. I'll just go to the back of the queue then, shall I, shall I?" The entire queue looked at each other again and went "Yes, yes, that sounds like a good idea. Excellent. Thanks for that" and words to that effect.
So he stormed off to the back of the queue and started another row because he tried to reclaim his original place in the queue which was now longer than it had been when he tried to queue jump. While still yelling about him not being as entitled as mothers.
The daft thing was, all of us agreed that if he'd just asked, we'd probably have let him go in front as he only had a couple of things.