I don't think my previous message got through. It was to say that cups have never been a noemal way of measuring in the British kitchen, so I don't think there is such a thing as a standard British cup. A google.co.uk search threw up US cup references (e.g. see http://www.gwydir.demon.co.uk/jo/units/volume.htm and http://www.cadbury.co.uk/EN/CTB2003/talk_to_us/faq/american.htm) . However, if you look at http://www.virgintogo.co.uk/template.asp?PageID=26&MenuID=26 you can see a cup defined as 250 ml, but I doubt if it's any sort of official measure.
A useful site is http://www.bbc.co.uk/food/recipes/ -- Chris KEENAN UK Metric Assoc: www.metric.org.uk
