Vanguard operations into Guernsey were very few and far between, mainly freighters and used to clear backlog of passengers when there was fog. Think they were more common in Jersey though.
Don't think the authorities were keen on the additional weight on the runway and limited there operations here.
Never recall ever seeing a vanguard at Guernsey , although I was very young I loved planes and clearly remember spotting regularly at the airport with my dad in the early seventies.