Paxboy, thanks for the pointer, never been into that forum before, always asked here or night stop for travel-related info if a search doesn't show up a suitable thread/forum.
Eutectic, thanks for the answar, exactly what I wanted to know.
Chucinchow, I did think about asking the UKBA, but after many years of getting authoritative but either wrong, misleading or useless answers from civil servants and large organisations, I decided to ask here - and it worked.
Cheers
UFO