I've removed an old window frame and it's left some fairly hefty nails and
screws which I need to cut flush to the surface and they are in a position
which is hard to get to with a hacksaw. I'm sure I've seen something on TV
which did the job easily using a small rotary disc. Just been to B&Q to look
at the multi tools (Dremel etc) which I thought was what I saw on TV (QVC
actually) but the bits seem more for sanding , grinding & polishing etc.

Can anyone recommend anything?

Thanks

Nodge