• Inquiry led by lawyer with no connection to past investigations
• Read the Guardian's 1999 investigation into the crash

Nick Clegg today announced a new independent legal inquiry into the 1994 Mull of Kintyre helicopter disaster that killed 29 people including top intelligence and anti-terrorist officers.

The deputy prime minister said the evidence surrounding the crash in western Scotland, which the RAF initially blamed on the two pilots, would be reviewed by a senior lawyer with no connections to previous reports.

An RAF board of inquiry ruled that the pilots – flight lieutenants Jonathan Tapper and Richard Cook – were guilty of "gross negligence". Their families have since been fighting to clear their names.

Clegg made the announcement in the House of Commons today during prime minister's questions as he was filling in for David Cameron who has flown to France to be with his ill father.

He told the Commons that the legal figure heading up the new investigation would have no links to past inquiries into the Mull of Kintyre accident.

"I am pleased to be able to confirm today we will be holding an independent review of the evidence of the Mull of Kintyre disaster, and I hope a review will be welcomed by those who died in this tragic accident," Clegg said.

"To ensure its complete independence, the review will be conducted by a respected lawyer who is independent of the government and who has not previously expressed a view on the disaster. The reviewer and the precise terms of reference will be announced soon.

Tapper's father, Mike, welcomed the announcement. He told the Guardian: "At last, we have a firm commitment from a government acting with integrity." All previous inquiries had been dismissed by a "stubborn" Ministry of Defence, he said.

"The fact is that the aircraft were brought into service with a completely new system which was in effect untried. The MoD knew damn well because Boscombe Down had told them," he added, referring to the MoD's aircraft research establishment which recommended grounding the Chinook fleet the day before the Mull of Kintyre crash.

Squadron Leader Robert Burke, a former Chinook test pilot who has been involved in compiling evidence in the case, said: "I am delighted, thrilled. It is the culmination of 15 years' work."

In June 1994 the Chinook helicopter crashed into a hillside near the Mull of Kintyre lighthouse in thick fog. Those on board, including top RUC special branch officers and a number of MI5 operatives, were on their way from Northern Ireland to a secret conference in Inverness. Top of the agenda at that meeting was a discussion on the possible loyalist paramilitary response to the forthcoming IRA ceasefire, which came two months later.

Among those killed was the deputy head of RUC special branch, Brian Fitzsimmons, and senior anti-terrorist officer Supt Ian Phoenix who had helped coordinate with the police and SAS the killing of seven top IRA men at Loughgall, Co Armagh in 1987. As well their immediate families among those who fought from the outset to clear the pilot's of any blame was Phoenix's widow, Susan.

Five years after the crash the government faced calls for a fresh inquiry when Computer Weekly magazine released evidence claiming to cast doubt on the reliability of the helicopter's engine control software, supporting campaigners' claims that the aircraft was at fault and not the pilots.

In February 2002 a House of Lords committee rejected the RAF's verdict and found that there were no grounds for blaming the pilots.

• Pregnant woman speaks of heartbreaking ordeal
• Regrets over decision to make second rescue dive

A mother who was forced to choose between saving the life of her teenage son or two-year-old daughter after her car ended up underwater has spoken out about her torment.

Rachel Edwards, 39, was driving her car with her 16-year-old son, Jack, and daughter Isabella, and two others when her car hit a pothole and ended up in a dyke near Boston, in Lincolnshire, last month.

Edwards, who was six months pregnant at the time, managed to swim to the surface through a car window but dived back down to the car, which was under 10ft of water, to rescue the toddler. Edwards said she was unable to rescue her son without letting go of her daughter and was forced to choose between the two.

"Since then I have spent every waking moment thinking about how I could have saved both my children."

She added: "I pulled Isabella out and I knew she was still alive. I tried to go back for Jack but I knew if I let go of Isabella then I wouldn't be able to get her back. I was just screaming and screaming."

She said that Jack's window had been closed because the toddler was asleep in the back of the car.

Recalling her own escape following the accident, Edwards said: "I took a deep breath and expected the car to stop sinking but as it went down I felt the car turn over. At first I didn't try to get out because I was in shock, but my window had been open so I managed."

In tragic detail, Edwards said that her last memory of Jack, who was sitting in the front seat, was of him putting his hand on her arm as the car began to sink. But the teenager was unable to escape after the accident after becoming trapped.

Edwards said she was haunted by the memory of her son's last moments.

"The last thing I remember about my son is, as the car was going down, he put his hand on my arm like he was protecting me," she said.

His two friends, Tom and Dave, who were also in the car managed to escape and raised the alarm.

Edwards and her daughter were helped out of the water and treated at the scene before being treated for minor injuries and shock at a local hospital. Isabella was soon able to return home with her family.

Edwards said she attempted to go back for her son but was prevented by paramedics who had arrived on the scene and has regretted it ever since.

The family had been travelling to Maplethorpe in Lincolnshire on 19 August for a holiday and Jack was due to collect his GCSE results five days after the accident.

Jack's father, Carl Brennan, who lives in Derbyshire and is separated from Edwards, has also spoken about the accident after more than 300 people attended the teenager's funeral in Dunmow, Essex, on Friday.

"It is a hard thing to put into words how I feel. You don't think you will ever have to bury your child," he said.

Edwards is due to have a baby boy in November, just three days after Jack's birthday. "Jack wasn't too pleased about that when I told him because he thought his 18th birthday next year would be overshadowed by the baby's," Edwards said.

But she described a happy son. "I was surprised at how many people turned up [at the funeral]. I didn't realise he had touched so many people."

She said that at primary school he once accidentally knocked over a little girl in the playground and had written to her to say sorry. "That was the kind of person he was," said Edwards. "He was respectful and always told the truth and he could be trusted immensely."