some of the begonia rex foliage might do the job as would Coleus. They come in many colour with reds as predominat colour.

thanks will look at them now

Some forms of Peperomia caperata are a good reddish colour too. I think there is a blackish-purple one also.

http://www.odla.nu/krukvaxter/images/bilder/peperomia_caperata.jpg

Some indoor Cordylines can be dramatic and red

thats stunning. thanks

Then there is the so called Beefstake plant (Perilla). Some of these really do have bright red leaves.

thanks for your help folks. looking forward to plant hunting now i know there are some suitable ones out there

Couple more suggestions - there's a plant called Ophiopogon nigrescens, commonly known as black grass ,which grows outside, but will grow inside on a sunny windowsill, although it won't like heat in the winter. Another one is Aeonium 'schwarzkopf' which has black leaves in sun and is slightly tender, so will do well inside. Something with red flowers that has a long flowering season with very dark, blackish leaves is Pelargonium Black Vesuvius (red) - that would do really well on a sunny windowsill.

thanks for that