Travel insurance covering pregnancy.

My wife is off for a weekend to London and will be 30 weeks pregnant at the time. She has a letter from her doctor saying she's fit to travel (though she may need a more recent one for it to be valid).

Can anybody recommend a good travel insurance company for her? Or even a good company in general who are likely to have a good policy for her?

Can't make a recommendation as we've never bothered with insurance travelling to the UK as we've always considered the E111 (forget the new name), to be enough cover?