Can you get radiator covers with the vent at the top.

[Karbea]

ie where the shelf bit is?

I've an idea, but it'll only work if I can find one... and I can't :(

something like this.

It's the sort of thing that any joiner could put together, but if you're planning to have the vent at the top INSTEAD of at the side, I have to say, it's likely to make the radiator very inefficient. I think radiator covers should be as open as possible to allow the radiator to, well, radiate, and for the warm air to circulate freely.

Drill some holes.