If you are prepared to go to London Carol Black at UCL. Actually she is proffesor Black and I'm not sure she hasn't gone into just acedemia.
I also had good treatment at the Nuffield in Oxford. I saw John Outhwaite - really nice and actually appologised for not realising my thyroid wasn't working and that's why the meds were not getting into my system as they should. When I moved to London he referred me to Prof Black so I wouldn't have to start again with a GP referal or be refred to someone else.
I've only seen these doctos as an NHS patient but both have been excelent.
If you're prepared to go to London, then St. Thomas' has a fantastic reputation. Patients go from all over the country to be treated there - NHS and private. They run a Lupus clinic but also deal with other autoimmune disorders such as; Sjogren's.
My rheumatologist isn't bad but she isn't fantastic either and I'm thinking of asking to be referred for another opinion.