DUBBED the 'bullet catchers', the officers of the VIP Protection Unit form one of the police's elite squads. Under their well-cut outfits, paid for with a special clothing allowance, they carry either a Glock 17 or a Glock 19 automatic pistol. 'This is one of the best modern hand guns around,' says a Hong Kong-based firearms expert. The 9 mm Austrian weapon is fitted with a magazine which holds up to 19 rounds, with a further one loaded in the breech, of hollow point ammunition, which, says the expert, provides better stopping power. The unit, headed by Chief Inspector Simon Patterson, comprises four teams each under a senior inspector. Until recently, it was the only part of the force that had armed women officers and was never publicised. It is possible they might be used during the current threat to the Chief Secretary. The equivalent role in the United States is carried out by the Secret Service. 'Their mission is to keep the VIP alive,' said a source. 'So getting the guy [assailant] is secondary to getting the VIP out alive. But they keep their actions very quiet.' Skilled in marksmanship and unarmed combat and with access to state of the art equipment, the unit was until recently controlled by the now disbanded Special Branch. It now forms a key part of the headquarters-based Security Wing. Officers from the unit, previously known as G4, protect visiting dignitaries and foreign heads of state, and do the same for senior local officials under threat. A risk assessment is carried out before visitors arrive and a certain number of officers will then be assigned. When the King of Tonga visited a few years ago, a team of at least four officers had the task of protecting him and trailed his limousine in one of the unit's white Ford Falcons - which carry extra fire power in the form of Heckler and Koch MP5 sub-machine guns. The unit has become skilled enough to run training courses. Agents fly into Hong Kong to learn the tricks of the trade - like wearing special pins under their lapels so they can identify themselves at official functions without having to produce a warrant card.