1) Kelly Brook. I read an interview with her grandmother years ago, which said that she had "terrible trouble with her teeth", and "wore braces for years". Apparently she was wearing lingual braces when she started presenting "The Big Breakfast"

2) Zara Phillips, of the British royal family. I saw a picture of her in a magazine years ago - she was young and wearing what looked like a retainer but was probably an active plate. Obviously didn't wear her retainer, as her inscisors are badly tilted in now! Maybe she'll get braces again...

3) Cerys Matthews from the band Catatonia - a few (4?) years ago she presented some music programme with another female presenter, and had clearly visible metal lower braces.

4) Kirsten O'Brien - BBC children's tv presenter, wore clear braces and elastics for a while when presenting a kid's art programme. She must have had them taken off early though, because her teeth were awful before, but still very far from perfect!

5) Athina Roussel, Granddaughter of Aristotle Onassis - have seen a few pictures of her when she was younger wearing a retainer. Never seen a braces picture though as I remember.

From todays (UK) Mail on Sunday - singer Cheryl cole has had veneers to change the shape of her teeth, and also wears invisalign. Says she quite often forgets to put it in, and thinks "Ah well, I'll just wear it tomorrow night instead". So I presume she's wearing a retainer now.

Another two I forgot - Ulrika Johnsson, many years ago on morning TV, mentioned that she had to wear "a brace" after someone remarked on her lovely smile. She said she had to wear it for " a couple of years" and "used to take it out to kiss boys". Maybe an active plate, maybe a functional appliance? Who knows!
Also Sara Cox, on her BBC radio show maybe 2 years ago, kept tripping over her words. She said it reminded her of being a kid when she just got her "first brace", and then proceeded to go on to give a great impression of talking when you first get a removable brace, and talked about clicking it in and out with ther tongue to freak out her friends!
I'm sure I will think of more...