Topaz, it should be safe to take up to a third of the height off the Leylandii without killing them. Any more than that is taking a risk.
I knew that we'd be putting the left-hand ones at risk by taking them down by 50%, but I was willing to try it as they're pretty healthy. I knew the ones at the back wouldn't take that amount of chopping so I said (at least 3 times) that they should only have a third taken off the tops. I said it to Mr Binns (boss/owner) when he came to price the job and to the 2 doylems who came to do the work...

Heigh ho...
So how to cope with it now it's done?
I was wondering about growing something up/over the massacred trees? I know that planting in the ground is pointless - bone dry & acidic - but I've got a big/deep dolly-tub which I could plant in? I was thinking maybe Clematis - Montana type which grows like mad, and/or some ivy for evergreen-ness? Any other ideas?

__________________
Sarah

http://wixypixies.blogspot.com/

“Tell me one last thing,” said Harry. “Is this real? Or has this been happening inside my head?”
“Of course it is happening inside your head, Harry, but why on earth should that mean that it is not real?”