F104G local production deals
The F104G was extensively built in the countries that bought it, and helped set up the German Italian fighter building industry. Would the British Governement be willing to sell the Bucc in the same manner, or would they want to sell finished aircraft off the shelf?
A late model F104S with 2 Karmoran missiles is a very capable antiship aircraft, and probably a lot cheaper than a Bucc. The Bucc is unbeatable as a long range low level strike aircraft, but when the LW bought the F104G it wanted an aircraft to fly mostly short range tactical nuclear strikes on soviet armoured forces.
A comparison btw an F104G and an early model S1 Bucc would not be as one sided as might appear, if cost, licensing manufacturing deals and rapid delivery are factored in. Countries that got the F104 later, with MB ejection seats and the bugs, operating routines worked out, like Spain and Turkey, had a lot less crashes/fatalities (Spain had 0 crashes with their 21 Starfighters)