Mental - I hang my head in shame.

Of course I do not use IE (I use Opera which views SVG wonderfully) so that wasn't an issue, but I do use Irfanview and that was causing the incorrect transparency view. I tried the image in Gimp and it looks fine, so does a jpeg export of the png. Testing on only one viewer is a lame thing to do and I am humbled :-)

Thanks,

Tony