Anglicans believe that liturgy expresses doctrine.And then argues that blessing of a same sex civil partnership would therefore change Anglican doctrine. Doesn't this imply that any Anglican service which isn't approved of by synod has the same effect? I didn't realise that an action by a local church had such powerful consequences. I'm off to plan a service!
And I'm sure that many Anglican Mainstreamish churches are quite happy to have unauthorized services when it suits them.