Dave goes to (busy) local Co-op to buy Sunday paper.
Joins queue of about 7 people (some with quite a lot of shopping) waiting in single queue for the two tills. No-one in a rush - locals chatting happily.
Notices a couple of (fullish) baskets tactically placed near the front of (but not in) the queue.
Watches with interest as a couple of elderly ladies (at this point they are still 'ladies') return at intervals to add extra items to baskets. This goes on for about ten minutes (the Co-op checkout process is not fast ... )
Queue moves on until Dave is now third (behind a couple of very pleasant young mothers and their happy children) - there are now a few people behind Dave too.
Elderly ladies return to baskets and assume position at front of queue.
Polite young mothers exchange glances, but say nothing.
Dave thinks "Stuff this" and says (very politely) : "I'm sorry - but there is a queue"
Elderly Old Baggage (no longer a lady) snarls : "My basket was holding my place - that's how we do things here"
Dave contemplates his options and then (with heart pounding) says : "No we don't - I've shopped here for five years and you get served in the order in which you physically join the queue".
Dave is backed up by the (now more confident) Nice Young Mothers and the people behind him mutter agreement too.
Old Biddies deploy the Death Ray Stare, but slink to the back of the queue.
On being served by the (lovely) checkout lady, Dave is given a big wink and a smile and a complimentary chocolate :+)
Anne - I am habitually of the "please go in front of me you've only got a few things" mindset - but only up to the point where someone presumes without asking.