Not sure that the poppies will come again this year but the shasta daisies should respond to the chop. Although i have thought about doing it over the years , have never had the courage to actually do it myself. I have so many shasta daisies perhaps writing this answer will tempt me to have a go on some of them.

I did it last year with one clump of Heleniums to get it to bloom later then the other 3 clumps. It worked OK. I just topped it by about 8 inches when it was about 2 foot tall. Monti Bon did it last programme........just bunched a helenium up and snipped off about 6-8 inches.

I've chopped solidago and sedum spectabile by about half in the past. It worked fine, though I'm not doing it this year because I felt it delayed the flowers a bit too much to be of greatest use to the bees and butterflies. I'm sure that varies with the weather, though.

Melchi...I'm with you. I tried it and being so far north it took so long for them to recover and reflower it was a pity. However, since they are already ruined by the wind, it's worth a try I would think...if they're too damaged to retie up again with supports. I think the Chelsea chop thing is better for the southern parts, but N. Humberside.....well, it might be ok.

I had large Leucanthemums collapse in the the rain last year - they were around 2 ft tall. I had no option but to chop them down. They did respond and produced flowers but not quite as many as I would have expected.

Well then, that's encouraging news Scottish :)

I have avoided the Chelsea chop this year due to the weather conditions, but I will be out there late next week to hack. I have tried it on most things. Some you win some you lose.

Well I have decided to go for it, nothing to lose really as they were looking so scruffy!

I think if plants have suffered from the wind and weather that there is nothing to lose by going for the chop, but agree with Karensusan that probably the further north you are, the more you risk reducing the flowers.