On the 30th of April 1980, six terrorists seized a group of hostages at the Iranian Embassy in London; the scene had been set for an SAS hostage rescue.  The codename for the assault on the Embassy to free the hostages was "Operation Nimrod". THE BRIEFING  The assault teams, Red and Blue, came from B Squadron who had just taken over counter terrorism duties and were code named Pagoda.  They were commanded by Major Jeremy Phipps.  The first members of the Squadron were in position around the Embassy within hours of the siege beginning setting up their sniper positions in Hyde Park.  Pagoda Team began preparing for a hostage rescue the moment they arrived.  They had built a replica of the five floor, 50 room building and established a command post on the sixth floor of Kingston House overlooking the Embassy. BACKGROUND After the armed terrorists had burst into the Iranian Embassy at No16 Princes Gate, Southwest London, they took 21 people hostage that included 15 Iranian Embassy employees, PC Trevor Lock and 5 visitors including BBC sound recordist, Sim Harris.  For six days the siege went on with negotiations for a peaceful solution being sought by the British Government; they had decided not to sanction the use of the SAS until there was proof that the terrorists were killing hostages.  One of the terrorists patience snapped and he shot dead one of the hostages, Abbas Lavasani, the Embassy's Press Officer. Just before 1800 Hrs on May the 5th, Lavasanis body was dumped on the pavement outside the Embassy.  Intelligence from bugs planted in the Embassy building itself proved that the terrorists were planning to murder more hostages unless their demands were met.  The time for talking was over.  At 1858 Hrs, the Home Secretary, William Whitelaw, authorised the SAS to take action.  At 1907 Hrs the Metropolitan Police formally handed over control of the siege to Lieutenant-Colonel Michael Rose, Commanding Officer of 22 Special Air Service Regiment.  "Operation Nimrod" was now active. By 1922 Hrs, Blue Team Assault party were in position in the gardens behind the buildings as well as in the front rooms of Number 15.  Red Team were in position looking down from the roof of Number 16 and once secured and ready for the assault gave the signal "Hyde Park".  At exactly 1923 Hrs the attack signal went out to all assault teams "London Bridge".  The eight soldiers from Red Team dropped off the roof towards the second floor balcony whilst the Blue Team rushed from the undergrowth towards the French Windows on the Ground Floor Terrace.  The whole operation very nearly went wrong at this point as one of the assault team NCOs got stuck in his abseil gear 15ft above the balcony.  As other Red Team members tried desperately to free him amid the tangles of rope, kit and bodies, a boot went through a window. GO! GO! GO! With the whole operation in danger of early discovery and possible failure, the Squadron Commander acted fast and screamed his orders over the radio net, Go! Go! Go!.  Operation Nimrod was on.  Red Team hit the balcony just as the explosives that had been lowered over the third floor sky-light went off On the Ground Floor Terrace, Blue Team was supposed to have gained entry by blowing in the ground floor French windows with plastic explosives; however, the NCO from Red Team was still stuck on his abseil rope above them and using the explosives could not be risked so they smashed their way in with sledge hammers. At the front of the Embassy, the roof top explosion signalled the arrival of other members from Blue Team on the front balcony of No 16.  Four Blue Team members reached the front window and were about to detonate a clumsy looking charge of plastic explosives against it when they spotted Sim Harris, the BBC man held hostage.  He was immediately told to get back out of the way as the charge blew in the window.  One SAS member then yanked physically, Sim Harris out of the room and ordered him to take cover on the balcony of Number 18. THE RESPONSE The terrorists were caught completely by surprise despite the assaults false start.  All of the other hostages had been divided up and separated.  The men were placed in the Tele room on the second floor whilst the women were placed in the Cypher room also on the second floor. When the diversionary charge exploded on the sky-light the terrorists were scattered between the first and second floors.  The terrorist leader "Awn" was in an office on the front first floor with PC Trevor Lock.  As soon as the assault started, PC Trevor Lock pulled his own gun that he had hidden concealed since the siege began.  He made an attempt to shoot Awn but could not do so in cold blood.  Awn turned instantly on PC Lock and a bitter struggle developed.  In the next office the window blew in and Blue Team made its entrance.  Running into the building, an SAS member broke into the fight pulling PC Lock away and shooting Awn dead on the spot. On the floor above, Red Team had run into difficulties.  They had burst in from the second floor balcony but had found the doors in the office locked and barricaded.  Their stun grenades had also set the room on fire.  On the ground floor, Blue Team had made their way through the library and were scouring the ground floor and basement for terrorists.  On the first floor, the gunfire had attracted the attention of the terrorist "Abbas" out of the Ambassadors office at the rear of the building.  He was shot by three SAS members.  For the members of Red Team, the rear office was becoming an uncomfortable and dangerous place to be in.  The doors were still barricaded and locked despite being riddled with gunfire and the room was now well ablaze.  One of Red Team, Tommy Palmer, lost patience and left the others.  Quickly he moved onto the adjoining window ledge; he saw one of the terrorists identified as "Shai" (Said) attempting to set the room on fire.  Palmer smashed the window and tried to shoot him but his MP5 jammed.  Meanwhile, the other terrorists, "Feisel", "Ali" and "Makki" had rushed into the Telex room and began shooting the hostages lying on the floor.  They killed one and severely wounded two others.  As they were shooting, they were joined by Said, who came running in from the back office with Palmer in hot pursuit.  The rest of Red Team finally broke through the barricades and upon hearing the gunfire from the telex room, were right behind Palmer as he kicked in the Telex Room door and killed Said with a single shot to the head.  The rest of Red Team followed Palmer into the room.