Thanks for your replies.

I thought about the digital TH2GO road but the racks were in the basement so cable lenght would have been an issue.

We managed to make it work in the end. we were using cat 5 extenders to do the run from the basement to stage and then vga loom from the cat 5 recievers to a VGA to HDMI converter. The problem was that the cat 5 recievers would intermittantly drop out for half a second due to the long bit of VGA between them and the VGA-HDMI converter. A VGA boost solved the problem.

Thanks again