According to my records, I think there may have been 2 Pan Am 707s that visited. The one shown in 1971 and N705PA visited on the 29th October 1975.
There was also a Pan Am B727 in March 1973, which was a Court Line sub-charter, following one of the Tristars bursting several of it's tyres on landing somewhere in Spain I think.
At one point there was a tape of ther arrival going the rounds. certainly Vintage ATCO was on it along with John Russell and Paul Donahue.