Monday, September 20, 1999 Published at 12:08 GMT 13:08 UK
Shadowy sister of the SAS
SBS troops lead the peace-keeping mission into East Timor
In terms of secrecy at least, the Special Boat Service are one up on their sister force, the SAS.
So while the one-impenetrable cloak of secrecy that used to surround the Special Air Service has been slowly lifted, many are unaware of the existence of the SBS.
The SBS is thought to number between 90 to 100 "swimmer canoeists", trained to a degree of fitness and stamina that ranks them among the toughest in the armed services.
Insights into the workings of the force are rare - new recruits must sign a confidentiality agreement - although one high-profile ex-member is Paddy Ashdown, former leader of the Liberal Democrats.
The origins of the SBS, which used to be known as the Special Boat Squadron, date back to the small reconnaissance and sabotage units of World War II.
In the post-war years, Mr Ashdown commanded SBS attacks on communist fighters in the jungles of Malaya, and led raids across the Borneo-Indonesian border. The service was also active in Korea and Oman.
In 1969, two members parachuted onto the QE2 cruise ship in the mid-Atlantic to tackle a bomb scare.
In Britain's 1982 war against Argentina over the Falkland Islands, the SBS was first to land on the islands and were also credited with re-capturing South Georgia from Argentine troops.
'First in Gulf'
In fact, the SBS's only loss in the Falklands was at the hands of the SAS, according to the memoirs of a former member, Duncan Falconer.
The SBS, which is based in Poole, in Dorset and has a frog as its emblem, was also said to be the first special forces unit deployed in the Gulf War.
In his book, First Into Action, Mr Falconer alleges that a map-reading error led to an SBS man being mistakenly shot dead in a neutral buffer zone. The Ministry of Defence said it was unable to confirm the claim.
The author further fuelled rivalry between the two special operations forces by claiming an SBS operative was generally trained to a higher level than his SAS counterpart.
Mr Falconer, who joined before the recently-tightened secrecy policy, described a gruelling selection procedure designed to only deliver the toughest recruits.
Potential recruits were tested with lengthy dives in "mostly zero visibility and freezing conditions".
"Long dives and swims followed by strenuous climbs up the sides of ships require a constant high degree of physical ability," he wrote.
More recently, the SBS gained notoriety for exposing flawed security at Dounreay nuclear power plant in Scotland, by breaking into the plant in one minute.