THE Home Office has obtained an interim order blocking the release of Thomas Quigley, Paul Kavanagh and Gerard McDon-nell, who were due out today, and of Patrick Magee, known as The Chancer, who carried out the 1984 Brighton bombing and was set to be released later this year.

Magee, who plotted to annihilate Margaret Thatcher and her Cabinet, was arrested in Glasgow.

He was spotted by officers tracking another IRA suspect and, in June 1985, arrested at an IRA safe house in Langside Road in the South Side.

The undercover work of RUC Special Branch Assistant Chief Constable Brian Fitzsimons, who died in the Chinook tragedy at the Mull of Kintyre in 1994, helped capture Magee.

If he were to serve the minimum 35-year sentence recommended by the judge at his trial, Magee would be 70 before he tasted freedom.

As a consequence of the early prisoner release scheme, he can look forward to reclaiming his freedom much sooner than that - though yesterday's move by Home Secretary Jack Straw to seek a review of the Sentencing Review Commission's calculation of his tariff puts a question mark over exactly when.

Magee was 35 when, in September 1986, he was given eight life sentences at the Old Bailey, seven of them for offences relating to the bombing of Brighton's Grand Hotel early on October 12, 1984, during the Tory Party conference.

He was sentenced for planting the bomb, exploding it, and five counts of murder - which attracted the minimum 35-year recommendation.

The eighth life sentence was for a separate conspiracy, to bomb 16 targets in London and at resorts around Britain. Four members of an IRA ''active service unit'' who worked with him on that project were also jailed.

Trial judge Mr Justice Boreham called Magee ''a man of exceptional cruelty and inhumanity'' who enjoyed terrorist activities.

Ironically the judge went on to voice satisfaction at passing such sentences. ''I must be grateful that in recent years legislators have raised the maximum sentence from a mere 20 years to life imprisonment for explosive offences,'' he said.

Two years earlier, Magee had checked into the Grand Hotel under the fictitious name Roy Walsh, staying there from September 14 to 17.

The bomber, who allegedly honed his skills at Libyan terrorist training camps, kept a low profile, preferring room service to the restaurant.

But his discretion hid a deadly purpose. In his room - number 629 - he primed a 20-30lb bomb, and hid it in a bathroom wall with a timing device set 24 days ahead.

Three-and-a-half weeks later, at 2.54am on October 12, the bomb blasted a gaping hole in the hotel's facade.

Though Mrs Thatcher - who was in the hotel working on her conference speech at the time of the blast - and her Cabinet escaped alive, Magee's bomb did kill five, and injured 34 others.

The dead were Sir Anthony Berry, 59, the MP for Enfield Southgate; Roberta Wakeham, 45-year-old wife of the then Tory Chief Whip Lord Wakeham; the Tories' north-west area chairman Eric Taylor, 54; Muriel Maclean, 54, wife of Scottish chairman Sir Donald Maclean; and Jeanne Shattock, 52, wife of the western area chairman.

The Home Secretary also obtained an interim order blocking the release of Thomas Quigley, Paul Kavanagh, and Gerard McDonnell, who were due out today.

Kavanagh and Quigley carried out a month-long London campaign in 1981, including the Chelsea Barracks bomb, which killed two passers-by and injured many Irish Guards, a booby-trapped bomb in an Oxford Street Wimpy bar that killed a bomb disposal expert, and the bombing of the Wimbledon home of Sir Michael Havers, then Attorney-General.

They were convicted at the Old Bailey in 1985 of three murders during 1981 and given five life sentences each.

Gerard McDonnell was the bomb making specialist and Magee's accomplice in the bombing of the Grand Hotel in Brighton in 1984.

He was given a life sentence in July 1986 for plotting to bomb British seaside resorts.

Sussex Police set about the mammoth task of tracing guests who stayed at the hotel in the preceding month. Some 800 people from 50 countries were traced and eliminated. Only Roy Walsh could not be accounted for.

The mystery guest's true identity was revealed thanks to a palm print on a hotel registration card, eventually matched with a print taken from Magee when he was first arrested as a juvenile in Norwich, where he grew up, years before.

Eschewing a public alert detectives played a waiting game, hoping the bomber would eventually reappear on the mainland.

It paid off, and in June 1985 he was arrested in Glasgow as he planned attacks on seaside resorts.

Magee was known as The Chancer because of his willingness to take risks, but one previous gamble had not come off, when he lost the little finger on his right hand as a bomb exploded prematurely.

In September 1994, then Prime Minister John Major ordered an inquiry when four republican prisoners, including Magee, were transferred from English jails to prisons in Ulster only hours after the first IRA ceasefire.