Hope this helps :
All three were orginally Vulcan B.Mk.1
XA892 delivered 1955, only the fourth built, used for manufacturers trials and A & AEE trials, to Halton as instructional airframe 7746M scrapped 72. Appeared at the Farnborough Airshow in 1956
XH479 delivered 28-3-58 Converted to B.1 A standard 1961, delivered as instructional airframe 7974M scrapped 73
XA898 delivered 3-1-57 230 OCU for its entire service life, then delivered to Halton on 25-8-64 as instructional airframe 7856M scrapped 71
A usefull link for serials and history :-
http://www.ajjcollection.co.uk/raf0.htm
and a photo of XH479 at RNAS Brawdy Air Day 1966
http://www.thunder-and-lightnings.co.../gallery4.html
PA-28