This was Air France, for quite some time they were the only operator.
According to THIS SITE, it was Seaboard World Airlines. Further elucidation by anyone would indeed be appreciated
Indeed I find it was Seaboard (first 747F aircraft delivered 31 July 1974), they beat Air France (delivered 4 October 1974) to it by two months. It was just these two aircraft that were built for some time. Seaboard operated "scheduled" Transatlantic cargo services (scheduled in quotes because, like most cargo airlines, the published plan was constantly switched around as loads and part-loads were presented or not, to normal or to off-line points), and came through London Heathrow and various Continental European points. They were bought out by Flying Tiger in 1980, who in turn were absorbed by Federal Express a decade later, that first 747F continuing in service with all of them. Flying Tiger had until this time been a US domestic and Transpacific operator, merging with Seaboard gave them worldwide freight coverage.
BSAA "Starliners" ? Here they are. A fascinating overall website of 1940s airline operation, by the way.
http://www.flywiththestars.co.uk/Pic.../Maps/maps.htm
Anyone any thoughts on that BSAA offspring ? You've all heard of them !