Thank you for your reply. This problem happened twice within a short time. However, he seems to have recovered very well. He is very happy where he is placed.
I have a very sheltered back garden, and even when there is frost at the front of our home, there is none to been seen in the back garden. I have a little area that i keep for the Bonsai. I built up a small garden not much more than 1 metre sq. Right in front of another long raised bed. All my baby plans are in there, and the 2 main ones (this one and the little conifer) stand on the ground beside it. They are sheltered there from the wind as behind the other raised bed is a tall wooden fence, to the right is the wall to our home, and to the left about 6' away is a small shed. Around all this, our garden has an extremely tall hedge, approx 12' high. So it is always a few deg. warmer in the back garden compared to the front.
As for winter, well, i am keeping a very close eye on them. I thought we were going to have a frost the other night, so i covered them in a huge sheet of bubble wrap! But it was fine. I also have a small 'plastic type' green house/cold frame. its only 4' high by about 2' sq. With 3 shelves in it. I am considering lining it with bubble wrap or something, including the shelves just in case, so that i can put them in there if and when i need to.
Otherwise, if it gets really cold/snow i will bring them into the back vestibule, as it stays reasonably cool in there, but they would still get plenty of light.
Hope i am doing all this right? I would hate to lose any of them now! Many thanks for all your help, best wishes Dianne