Ascot is used by All RAF transport aircraft when route flying. RR1000 series, Bae146. RR2000 series KC-30, RR4000 series being the A400M, RR5000 series C-130 and RR6000 series C-17. KC30s use Madras and Tartan call signs when tanking in the UK. 400 sometimes use Comet call signs when undertaking tactical flying with C-130s using Jigsaw.
RAF fast jets often use the Ascot call sign when in transit overseas when accompanied by KC-30. The ASCOT call sign dates back to the days of RAF Air Support Command, standing for Air Support Command Operation Task.