Legal Question for UK

I've got a HP plot bunny I'm working on, and I need to know about same-sex parents' adopting in the UK. Specifically, if one person is the biological parent of a child, can his/her same-sex partner adopt that child? (The other biological parent has given up parental rights.) If the answer is yes, then do you know in what year that became legal?

I did try looking it up, and I will gladly research it more later, but I thought someone might already know.