D is 2y10m and has been potty trained for aout 5-6 months, I think...

in the last 2 weeks, she has started to have "accidents" at nursery- up to 6 times a day! Some wees, some poos. I am happy that she doesn't have an infection- wees in the potty are nice and clear, and she doesn't have any stinging/ burning. We have tried star charts with no success (don't think she really understands the concept), stickers (she's not bothered whether she gets one or not!), bribery with the promise of a chocolate (Milky Way Bite-Size Bar)if she comes home in the same pair of trousers she went in- worked for one day only- maybe a fluke!

Here's the strange thing...when she wets herself she has been insisting on wearing "nursery trousers" instead of the clean trousers we put in her bag. If she gets nursery trousers she has no more accidents. Today she had one accident this morning, then was put in nursery trousers and had no more till she was picked up at 5 pm. So, I know she can do it, but why won't she?

Nursery trousers tend to be soft velour and in pretty girly patterns and colours, so I'm tempted to go out and buy her some, but wouldn't that be reinforcing her behaviour?

What should I do?

It sounds to me as if she's deliberately wetting herself to get the nursery trousers, so I'd be tempted to go and buy some similar trousers myself - if she's wearing something she's comfortable and happy to be wearing, perhaps the wetting will stop. I don't think it would be reinforcing her behaviour; children of this age have definite preferences about what they wear, and this may be what's happening. Perhaps you could let her help to choose her own new trousers, if she has some that she's happy to wear then she may keep them on and stay dry, which is what you're looking for, and this will reinforce the behaviour you actually want from her.

Perhaps if you let her help to chose her own new trousers

Go buy the cute trousers, Tissy. If it works, it works. Give yourself an easy life.

take her to tescos and pick up some lovely soft leggings with her. thin ka 2pack is about £5-8. think she is asserting her taste in clothes.