I've just had a look in the book itself, XH535 was flown to Edwards for ground radio tests for the Skybolt system. Tony Blackman and Dickie Martin flew the Vulcan out there via Goose Bay, cruise climbing from 47,000 feet up after departing Goose. When positioning the aircraft on the lakebed for the trials, the local pilot, who was along to provide directions, got them into a cul-de-sac and to get out of it they went across some stones, ruining a complete set of tires in the process. It did not delay the trials, but a set of tires had to be flown out and it took a few weeks before the aircraft was ready to head home. Tony Blackman then took Fitz Fulton up, letting him fly the Vulcan. During that flight, they managed to take the formation photos shown above. In return, Fitz Fulton let Tony fly with him in B-52 20008, and he organised a flight in a B-47 for him with Jack Allevie. Both flights are illustrated by the photos showing Tony in front of the respective Boeing types (see post #10).
I agree that the caption for the first image that triggered this thread is wrong. Just comparing the two images on the page, it is clear that they are not of the same B-52.
Returning to the UK, they arrived around dawn but were unable to get into Woodford due to the weather and lack of an ILS, and diverted to Manchester.
XH535 was the Skybolt radio programme development aircraft. It later crashed near Amesbury.