Many try to get into the Special Air Service regiment. Most of them fail. Out of an average intake of 125 candidates, the grueling selection process will weed out all but 10. There is now a joint selection process, UKSF selection, for both the SAS and SBS.

Selection Phase 1 - Endurance:
The first phase of selection is known as the endurance or 'the hills' stage. This is the endurance portion of selection and not only tests a candidate's physical fitness, but also their mental stamina. To pass this phase, a high level of determination and self-reliance is vital.

The hills stage lasts 3 weeks and takes place in the Brecon Beacons and Black Hills of South Wales. Candidates have to carry an ever-increasingly-heavy bergen over a series of long timed hikes, navigating between checkpoints. No encouragement or criticism is provided by the supervising staff at the checkpoints. SAS Directing Staff (DS) are fully-badged members of the regiment and leave each candidate to their own devices. This can be a marked contrast from the selectee's experience in their parent units. They would be used to their instructors shouting constant instructions at them, along with encouragement and abuse. The demands of life in a special forces unit require each member to be self-motivated.

The endurance phase culminates with 'the long drag', a 40 mile trek carrying a 55lb bergen, that must be completed in under 24 hours.

Selection Phase 2 - Jungle Training:
Those who have passed stage 1 have to then pass jungle training. Training takes place in Belize, in the heart of deep jungles. Candidates learn the basics of surviving and patrolling in the harsh conditions. SAS jungle patrols have to live for weeks behind enemy lines, in 4 man patrols, living on rations. Jungle training weeds out those who can't handle the discipline required to keep themselves and their kit in good condition whilst on long range patrol in difficult conditions. Again, there is a mental component being tested, not just a physical. Special Forces teams need men who can work under relentless pressure, in horrendous environments for weeks on end, without a lifeline back to home base.

Selection Phase 3 - Escape & Evasion & Tactical Questioning (TQ):
The small number of candidates who have made it through endurance and jungle training now enter the final phase of selection. The likelihood of a special operation going wrong behind enemy lines is quite high, given the risks involved. The SAS want soldiers who have the wherewithal and spirit required to escape and evade capture and resist interrogation.

For the escape and evasion (E&E) portion of the course, the candidates are given brief instructions on appropriate techniques. This may include talks from former POWs or special forces soldiers who have been in E&E situations in the real world.

Next, the candidates are let loose in the countryside, wearing World War 2 vintage coats with instructions to make their way to a series of waypoints without being captured by the hunter force of other soldiers. This portion lasts for 3 days after which, captured or not, all candidates report for TQ.

Tactical Questioning (TQ) tests the prospective SAS men's ability to resist interrogation. They are treated roughly by their interrogators, often made to stand in 'stress positions' for hours at a time, while disorientating white noise is blasted at them. When their turn for questioning comes, they must only answer with the so-called 'big 4' (name, rank, serial number and date of birth). All other questions must be answered with 'I'm sorry but I cannot answer that question.' Failure to do so results in failing the course. The questioners will use all sorts of tricks to try and get a reaction from the candidates. They may act friendly and try to get their subjects chatting; or they stand inches away from their subjects and scream unfavourable remarks about the sexual habits of their mothers. Female interrogators may laugh at th