Thanks so much everyone! Will definitely sit down with her this evening and start browsing.
Albus - her feet are on the narrow side, but will have a look. I love the boots on the Marisota page you linked to but she may not... 
BigBro - I'll try Clarks, she may go on strike on the grounds of association with school shoes - she's just started Sixth Form and wants only to be achingly cool - but we may have joy.
SnowFilled - Didn't know Brantano went over size 9 - and there's a branch only fifteen miles away.
Bolograph - Is that the street I heard mentioned on Women's Hour while driving and unable to stop and make notes!? Apparently about four larger size independent shoe shops all in a row?
hennybeans - again thanks for website suggestions. We may be going to the US, but not for a few months, however I will ask the sister who lives in San Francisco if Payless Shoe Source is on the West Coast. It might even be worth the inordinate cost of shipping! I absolutely agree about quality. DP is the source of the large size feet for both our daughters (the other seems to have stabilised at 8.5), he is a UK 15 and apart from boots that he spent ??200+ on, his shoes never last more than a few months. At this stage, cheap and not very long lasting is okay, apart from her hiking boots for DofE and Geography field trips etc, which I have already spent serious money on. She's young enough that she'll want new styles each season.
Kidnapped again thanks for names to search for.
Bore I take it that's Walcot Street in Bath?
I'm going to ask for this to be moved into something that won't disappear after 90 days, which is I think what must have happened to the thread I thought I'd moved into Watching last year. Style and Beauty I imagine is the right place, but I thought I'd get more replies in Chat, and I think I was right.
Once again, thanks everyone!