 The United Kingdom bought versions based on the U.S. Navy 's F @-@ 4J for use with the Royal Air Force and the Royal Navy 's Fleet Air Arm . The main differences were the use of the British Rolls @-@ Royce Spey engines and of British @-@ made avionics . The RN and RAF versions were given the designation F @-@ 4K and F @-@ 4M respectively , and entered service with the British military aircraft designations Phantom FG.1 ( fighter / ground attack ) and Phantom FGR.2 ( fighter / ground attack / reconnaissance ) . Initially , the FGR.2 was used in the ground attack and reconnaissance role , primarily with RAF Germany , while 43 Squadron was formed in the air defence role using the FG.1s that had been intended for the Fleet Air Arm for use aboard HMS Eagle . The superiority of the Phantom over the English Electric Lightning in terms of both range and weapon load , combined with the successful introduction of the SEPECAT Jaguar , meant that , during the mid @-@ 1970s , most of the ground attack Phantoms in Germany were redeployed to the UK to replace air defence Lightning squadrons . A second RAF squadron , 111 Squadron , was formed on the FG.1 in 1979 after the disbandment of 892 NAS . 
