As moves begin to honour one of the Scots involved, Sandra Dick reflects on 40 years since SAS troops ended the Iranian Embassy siege.

The white stucco facade of Princes Gate’s terraced buildings turned dusty pink as the sun began to set over London, bringing a bank holiday Monday to what appeared to be a peaceful close.

Across the nation families were watching the snooker, Coronation Street and holiday movies. The title of one, Detour To Terror, would prove to be remarkably appropriate.

It was 7.23pm. And as the BBC unexpectedly switched its coverage of Alex Higgins and Cliff Thorburn at the Crucible Theatre to beam live from central London, viewers were about to be whisked from the comfort of their living rooms into a real-life action drama.

The sight of men clad head to toe in black abseiling down the walls of the Iranian Embassy, crawling across its first-floor balustrade balcony, defying pouring smoke and leaping flames to storm the front of the building, would be like nothing played out on British soil before.

The rattle of gunfire competed with screams and yells from inside the building.

Outside, smoke billowed into the blue sky, pigeons scattered and the unflappable Kate Adie described what everyone was watching against a soundtrack of barking dogs and violent explosions.

For those inside the embassy, now in their sixth day of being held by gun-toting terrorists, it was life or death.

And for the elite soldiers who brought the 1980 Iranian Embassy siege to an extraordinary close, the day’s high-adrenalin events would remove the cloak of mystery shrouding their squadron and conclude in perhaps the most unremarkable of manners, with a much-needed burger and a cup of tea from a roadside van.

Now, 40 years since Operation Nimrod saw the SAS end the Iranian Embassy siege with the safe release of 19 hostages, plans are being made to recognise the bravery of one of their team – the Scot who, watched by millions of viewers, led the astonishing assault on the front of the building.

Prime Minister Margaret Thatcher's decision to let the world witness the British response to terrorism meant the cameras were able to capture Lance Corporal John McAleese and his SAS comrades, in black-as-night Royal Tank Regiment overalls with respirators covering their faces, swarm across the front of the building.

Within seconds, a wooden frame attached with explosives had been pinned against a first-floor window with McAleese – later unveiled to be a sunken-cheeked Scot with a handlebar moustache – standing aside only briefly while it tore apart glass and stone, sending flames leaping into the sky.

Meanwhile, at the rear of the embassy, other SAS teams were at work: one team crashed through a skylight, others burst into the building throwing canisters of CS gas and despatching terrorists – their faces memorised from photographs – as they went.

Rusty Firmin, who led Blue Team as they charged the rear of the building – recognisable in photographs as the only SAS man not wearing gloves – is now leading a campaign to mark the Scot’s achievements in the operation and his military career.

Plans are under way for a bronze bust of McAleese, who died aged 62 in 2011, to be placed on a granite plinth in his home village of Laurieston, near Falkirk. “He was an amazing soldier, strong as an ox, brave and fearless,” Firmin recalls. “He was a great character.

“There should be recognition for him and what he did.”

The most famous episode in British counter-terrorism history had started six days earlier, on April 30, 1980, when six Iraqi-trained heavily armed terrorists claiming to be from the Democratic Revolutionary Movement for the Liberation of Arabistan burst into the Iranian Embassy building in London’s Prince’s Gate.

While negotiations to release the 26 hostages – among them four Britons – were led by the Metropolitan Police, behind the scenes at a military camp in Herefordshire some of the country’s best-trained soldiers were already prepared for action.

But according to Firmin, their focus wasn’t London. “We had just taken over from another squadron and were waiting to go on exercise in Northumberland,” he explains.

“Everyone was doing their own thing when a series of bleeps went off on our pagers. Most people thought it was the start of the exercise, but the numbers that came up were four ‘9s’, which meant an operation.

“We thought maybe someone had pressed the wrong buttons,” he recalls.

Over the following days, police negotiators kept the terrorists talking long enough for around 60 members of 22 Special Air Services Regiment 56 to take over the neighbouring building. From there, they used listening equipment to eavesdrop on conversations through the wall and memorised the faces of the terrorists from photographs.

“We found out how many terrorists, what weapons, ammunition, how many hostages – a few had been released and they gave us some information too,” recalls Firmin.

“The gas board was outside drilling, some Heathrow aircraft were diverted to fly overhead to make more noise.”

Hopes that the terrorists would give in vanished when, at 1.45pm that Monday, their second in command shot dead one hostage, the Iranian Embassy press attaché.

News reports showed plainclothes police officers, hunched to protect themselves, bravely retrieve his body from the blood-stained steps.

With clear evidence of murder and the threat that hostages would die every 45 minutes, command was switched from the police to the SAS.

Crucially for television viewers around the world, there were clear instructions from Downing Street that no smoke bombs would be used to shroud the assault. Instead, the world was to see how Britain dealt with terrorists.

“We knew what we had to do,” adds Firmin. “It took 16 minutes to get into position covertly. We didn’t want to rush the building straight away, because there’d been no more shooting. We thought if we could get in there covertly, they wouldn’t know what was happening.”

The command “go, go, go” set the SAS assault into motion.

On the first floor, McAleese’s boots were melting in the heat of flames ignited by magnesium in the stun grenades and fuel which the terrorists had poured over furnishings. Downstairs, Firmin and his team set about clearing other floors and leading hostages to safety.

One, PC Trevor Lock, ended up in a deathly grapple with terrorist leader Awn Ali Mohammed, a 27-year-old code-named Salim, the service pistol he had concealed for days now pointed at his captor’s head – an incredible act of bravery that saved at least one SAS soldier’s life.

“I still think about it every day,” the retired police officer said in an interview to mark the 30th anniversary of the siege. “It is the classic symptom of post-traumatic stress, isn’t it? It never goes.”

Dozens of SAS soldiers swarmed from floor to floor, identifying hostage from terrorist in choking smoke while flames licked through the building.

“Six floors, 56 rooms,” Firmin adds. “No-one knew exactly where all the terrorists or hostages were. The lads did what they had to do.”

Shakir Abdullah Radhil, known as “Faisal”, second in command of the terrorist group made a bold but ill-fated attempt to escape by joining a group of hostages as SAS soldiers cleared the rooms.

“There was glass everywhere, people were slipping, tripping. We were trying to identify them as they came past us on the stairs from the pictures we’d seen,” adds Firmin, who collaborated on the Netflix film of the siege, 6 Days.

“One guy was trying to shield his head with his jacket. You don’t do that unless there’s something wrong.

“My mate hit him across the back of the head and we saw the grenade. I fired two bursts, split-second, at arm’s length. He ended up on the bottom of the stairs and everyone carried on.”

It was over in just 11 minutes. One terrorist survived – Fowzi Nejad was later sentenced to life in prison. Now released, he is thought to live in Peckham.

As the dust settled, the SAS team returned to the Regent's Park barracks to be congratulated by the Prime Minister before making their way back to Hereford.

While the world got to grips with a new obsession – the mysterious SAS – the men behind the slickest ending of a hostage situation ever seen had other thoughts.

“We stopped off in Cirencester,” recalls Firmin. “There was a 24-hour burger van. We stopped, had a chat, a cup of tea and went home.”