SF 'Big Four'; Para, RM, SAS and RAF Regt.
Not wishing to belittle others, but D SF only covers 21/22/23, 18 Sigs and 63 Sigs, SBS, SRR and SFSG. SFSG is based on the former 14 Int Coy drawing from all Services. RAFR, mainstream RM and Para are not SF, by any stretch.