phantomstreaker,
My father was an exchange pilot (RN) on VF121 during the Vietnam War. He did not ever fly over there and told me that UK aircrews were not authorised to do so due to the clear fact it was not 'our' war.
However, there has been at least one post on this forum (maybe more, can't recall), stating that a small number of aircrew did. Not sure myself. I would have thought my father would have told me as years went by. He is no longer with us so can't ask him.
TN.