IIRC the Release to Service permitted rolling G of 1.75 on a one off war mission, We were not permitted to practise the escape manoeuvre. I think we went to about 1.5 g during evasive bomb runs.
As for the alleged barrel roll, it was stated that the two films of the alleged roll were not video files but constructed from a number of still frames.
As the film was a construct it is also open to deconstruct and potentially invalid as evidence.
"Did you?"
"No, I didn't"
~~
"Call expert witness #1"
"What is your expertise?"
"I am a former display pilot."
"Did you observe Vulcan XH558 perform a manoeuvre where the aircraft became inverted and otherwise known a a barrel roll?"
"I saw the Vulcan from .... and saw it bank away. I did not see it the whole time."
"Call the next witness."