Do you mean SFS?
The HP-SFS (Safe-Fast-Shooting) is a current variation on the Hi-Power Mark III with a modified firing mechanism. After the weapon is loaded, the hammer is pushed forward, which automatically activates the safety catch. When the shooter is prepared to fire, the safety is pressed down with the thumb, releasing the hammer to spring backwards into the usual, single-action position. A similar system is available for modifying Colt M1911A1s. Magazines are interchangeable with the Mark III and others.
If you are inquiring of this being an British SAS issued P35 aka L9A1...I would highly doubt it.
The L9A1, was the British designation for the military version of the post-1962 Hi-Power, and is marked 'Pistol Automatic L9A1' on the left side of the slide. It started to replace Inglis variants in British service from the late 1960s, and the two types remained in service together until the Inglis variants were finally retired in the late 1980s. It is still in service with the UK military forces, although now fitted with the more ergonomic Mk2 ambidextrous safety and grips. The L9A1 was also widely used by other Commonwealth armed forces. The Hi-Power was the pistol issued to the British Special Air Service throughout the Cold War era. It was phased out in 2013 and replaced with the Glock 17. (Error- The SAS began using the Sig 226 in the mid-late 1980's)
18Z50