Thanks guys.
Steve thanks for the info. Hey I'm chilled!

Joe yes a domestic helper's visa to work as nanny for her family travelling to the UK.
6 months was granted from late March 2010. They had no idea if they would be staying a few months or a few years so they only got her a 6 month one from the Brit Consulate in Hong Kong. It's likely they'll be here permanently now.
I don't know if her domestic visa can be extended. I am assuming it can't, ie she has to leave then reapply then come back again, but I'm happy to marry her if that expedites matters. Whether it's while she's here or as part of a spouse visa application.
I'm trying to ascertain the best route to having her here permanently.
We've been romantically involved for about 14 months as I've worked on and off in Hong Kong recently.

Thank you again for the replies.