He broke the law, regardless of how stupid the law is and who he was.
If a SEAL was pinched w/ a unregistered M60 in his garage, he would be arrested just the same as the SAS guy. I have no sympathy for the situation, as gun owners we need to live to the letter of the law.
If the UK wants a gun, move here and become a citizen. It is very common to do this. I sell a gun at least once a week to a new US citizen from the UK or Europe.
Ed Brown 1911 fan #1
HK45 fan #2
FN PS90SBR/FiveSeven fan#3