Red Maple-Half with no leaves

Mine did this this year - I lost about half of the tree. I cut off the dead part down to where I can see little red shoots appearing. The Dissectum also did this two years ago when it was in a pot in a position that caught the wind. I had to cut off a large branch - but it has grown well in its new sheltered place and looks great! Yours has either got cold wind damage or been caught by the frost - so bite the bullet and cut it back (A feed would also give it a boost.)

This happened to my Acer Palmatum too. In my case I think it was midday sun during our hot dry Summer that did the damage. I moved it to a spot where it is in shade for most of the day. I cut off all the dead branches last year. It is doing really well now and growing steadily. It has survived our cold winters very well. We are a lot colder than UK, equivalent to zone 6.