The shock of being moved from the outdoors to the conservatory is what is causing the problem, especially if you are heating the conservatory. I would suggest putting it back out and only bringing in overnight to start with - sort of the reverse of hardening something off! Oh and water well!

i Moon growe,thank y,hope things work outou for answering back ,ihave done what you said,it's full of bloom and it seems a shame to lose it.

Also make sure that the conservatory has a similar sun exposure to where you have been keeping it in summer. As long as the conservatory has decent light, a difference is rarely fatal, but it makes the transition more stressful for the tree.

I've just been to see my friend up the hill, Filomena, whose family owns lemon groves in Calabria, and asked her advice. Moon grower is spot on. It's too soon to move it indoors permanently, and the overwintering site should only be heated enough to keep it from freezing. Light is important, and reduce the water gradually but not completely. They don't appreciate high winter temperatures. Are you expecting frosts yet in the UK? Surely not? She also said that if you follow this advice quickly, you just might get more your leaves back again. Good luck!

thank you all for answering my question,it has been great to get an answer for which i am going to do.