Niti was the first one to correctly guess that I was of course, dressed as Wonderwoman. (Niti - can you leave your address in the comments please - I won't publish it).
Thanks everyone so much for playing along, it was so much fun to read all your comments. People who actually know me didn't guess correctly! I'm definitely going to do another competition soon.
Looking at this actual photo of Wonderwoman my first thought was; that's not what Wonderwoman wears! Where's the blue cape, the woolly tights, the er, red Clarks sandals? Then I realised that my mother must have very wisely toned the costume down for me. (I still insisted on dressing as a prostitute on Halloween the following year - snood as a skirt, nice!)
And Brown Paper Bag Costume: if I could remember who you were, I'd give you a prize too. I crack up every time I look at it - the matching brown slacks and shoes just kill me.