Typhoon (new version) with Battle of Britain 70th anniversary markings

As some of you may know there are three Typhoons at RAF Coningsby with Battle of Britain 70th Anniversary markings.

They are:-

ZJ912 of 17Sqn marked YB-F which i belive is the markings of a Hurricane flown by F/O Count Manfred Beckett Czernin

photo here http://www.flickr.com/photos/last_lightning/4856100209/

ZJ941 of 3Sqn marked QO-J which carries the name P/O J. Lonsdale RAFVR who flew Hurricane QO-J during the battle

photo here http://www.flickr.com/photos/last_lightning/4853280107/in/photostream/

Finally 29Sqn Typhoon ZJ805 which has the markings S-RO

A photo here (not mine) http://www.flickr.com/photos/manxnorton/4884764316/

Now my problem is that i cannot find anything about S-RO, I think its the markings for a Blenheim but beyond that I have no idea

I was also thinking that the markings may be wrong, that thay should have been SR-O but the one photo i have seen of a 29sqn Beaufighter marked B-RO quickly put that theory out the window.