Ohh, all these people that have nursed over a year! People look act and look so surprised that I'm still nursing her but this is encouraging.
I've noticed a pattern in when she is biting and it's towards the end of her feed when she's starting to loose interest so at the first sign of her slowing down I'm keeping careful watch on her so as soon as she stops her feed I can reposition her so she's just having a cuddle instead. If she does sneak in a little bite then I'm going to try the methods suggested here and see if they work for us.
One person suggested to me to say "ouch" very loudly and all that achieved was to make her jump which made her bite harder.
I'm sure we'll find the best solution for us soon or better still she will stop doing it.