British Overseas Airways Corporation, incorporated from Imperial Airways and British Airways in 1940.
“Speedbird” was B.O.A.C.’s callsign until 1974, when B.O.A.C. was folded into British Airways (callsign: “Speedbird”).
This is more than likely a Boeing 707-420 with the Rolls-Royce Conway 505/508 turbofan engines. The card dates from the early 1960s or so, when B.O.A.C. began adding the 707-420 to the fleet.
Uncle Bob's Pix 