Thanks, Bossy. I hd no idea what I would set loose!
Those of you who have proposed on-line shopping as the answer are probably right in terms of reducing stress and potential trolley accidents/hygene issues. However, if I did my shopping on-line, I would deprive myself of a much needed outing and contact with other adults, especially as bad weather approaches. Before you start shouting about the library, museums and toddler groups, I take my kids to one of these nearly every day of the week, and I also take them to a farm shop regularly. Moreover, I think it is good for them to get experience of supermarket shopping, and it is not always a difficult experience: my ds1 actually likes helping put things in the trolley and on the conveyor belt, and there are other important lessons to learn from being taken into the shop; for example, we have been working on 'looking at' as opposed to 'buying' toys we like, with big improvements in a short time.
Paolosgirl, sorry if I sounded sarcastic last night, but I was on my 2nd glass of wine, and I hope you can see from what I've just written that I do take discipline and good behaviour seriously. As someone else has pointed out, I think it is important to choose my battles, as my ds1 is exceptionally strong-willed. Regarding the trolley, I never had considered it as a potential problem till now, and I am 'loathe' (get it?) to draw yet another battle line with him about something which seems a relatively minor risk, especially since he is quite happy to shop with me now, is generally well-behaved, and has never given me any indication that he would attempt a dare-deivl move.
Having said this, I may remove his shoes in deference to the germ-phobics. Or then again, I may not!