Hi Adam,
I started bjj training under Ronaldo earlier this year at his clubs in the Tokei and in Victoria in London. He is a brown belt under Ze Marcello and teaches alongside another brown called Eduardo.
I personally think he is excellent, at least in my experience the classes are well taught and the class is very friendly. Its usually split between something like a 15 minute warm up, 45 mins on a couple of techniques and 30 mins sparring.
His website is below if you don't already have it.
cheers,
John G
http://www.ronaldocampos.com/