Are you sure that 818 went tanking?
When I escorted my Whirlwind brethren through 818 in 1966 at Marham, Ops having given me the keys, it was finished in grey green camouflage so I presume it was a Main Force aeroplane.
When I saw it at Cosford it had just arrived and the fuselage was scarred along the wing mountings where there had been some serious metal cutting. IIRC the Valiant core was the bomb bay roof with large webs that enclosed the engines. The wings were tacked on to these with rivets.
It was obvious from the state of 818 that the webs had been cut so as to remove the wings, therefore the wing refits had to be botched.