LONDON, JULY 30 -- Ian Gow, a senior Conservative member of Parliament who was an outspoken foe of the Irish Republican Army and a close friend of Prime Minister Margaret Thatcher, was killed today in a car-bomb explosion at his home.

Gow was backing his sedan out of the family driveway in the village of Hankham, 50 miles southeast of London, when a bomb placed under the driver's side ripped through the car, according to police.

Gow's wife was in the house and ran out to aid her husband, but he died shortly after an emergency team arrived. There were no other injuries.

Gow, 53, was the first public figure to be killed in a wave of bombings and other attacks on the British mainland in recent months. While the IRA has claimed responsibility for previous bombings, it did not immediately do so in today's attack. But police said Gow's name was among more than 100 on an IRA hit list discovered in December 1988 and that the bomb -- 4.4 pounds of plastic explosive -- appeared to be an IRA device.

As Thatcher's parliamentary private secretary during the first four years of her premiership, Gow served as the main liaison between her and other members of Parliament from her Conservative Party. He had daily contact with Thatcher in those days and was counted as one of her most ardent loyalists.

Thatcher, dressed in black and speaking in a subdued, hesitant tone far removed from her usual public manner, paid solemn tribute to Gow while talking to reporters outside her office at 10 Downing St. She called his death "a grievous loss both to me personally and also to the parliamentary life of this country and to his constituency."

"Every day for four years he went through that door behind me and was in Number 10 and Parliament. I do not think I could have done those four years without Ian," she said. "He made an enormous contribution to everything I have been able to do."

Asked if Gow was aware of the risk to his life, Thatcher, who narrowly escaped harm in a 1984 IRA bombing, answered as though speaking of herself: "I think intellectually you always do, you know the risk, {but} I think you perhaps think that it won't happen to you."

After a pause, she added, "It's still difficult to believe that Ian won't come in and say, 'Come on, things are not very easy, come and have supper.' "

A 16-year parliamentary veteran, Gow was a popular figure with old-fashioned, gentlemanly manners and a wry sense of humor but a blunt, relentless, bulldog approach to debate. He was a solid member of his party's right wing.

He was also a fierce hard-liner on the issue of British rule in Northern Ireland and chairman of an influential Conservative parliamentary committee that sought to hold the government to a no-retreat policy. He also co-founded Friends of the Union, a lobbying group for loyalists in Belfast and London.

In 1985, he broke briefly with Thatcher, resigning as a deputy treasury minister to protest the signing of the Anglo-Irish agreement between London and Dublin. At the time he objected to giving the Irish government a consultative role in Northern Ireland affairs, saying it would only "prolong and not diminish the agony" of the province.

Last week, Gow appeared on BBC television to bitterly condemn the IRA for an attack that killed three police officers and a Roman Catholic nun in Northern Ireland.

"These murders are as odious as they are futile," he said. "Once again wives have been turned into widows and children into orphans. And for what purpose? There is a terrifying, perverted purposelessness in this attack as in all IRA attacks. . . . Their campaign is totally futile, is causing great misery and it will never, never win."

Mark Stewart, who was driving past the house just after the explosion, told reporters: "I looked into my rear mirror and saw the car in bits all over the place. I stopped my car, got out and ran back. When I got there it was a terrible mess."

Thatcher traveled to Hankham later in the day to visit Mrs. Gow, view the site of the bombing and plead with the lawmakers to heed warnings about their safety. Police said Gow had been warned about the threat to his life, but friends say he had chosen to live openly. His home phone number and address were in the local telephone directory.

"His connection with the prime minister made him an ideal candidate for assassination," said Ian Geldard, editor of a terrorism newsletter here. "He must have been well up on their list of targets -- perhaps in the first half-dozen."

Gow's killing is expected to bring calls for increased security for members of Parliament. But authorities said it would be impossible toprotect all 650 adequately. The bombing, said George Churchill-Coleman, commander of the police anti-terrorist squad, was "simple to do, so simple, in fact, it could be done every day of the week."

IRA operatives have carried out nearly 20 attacks in mainland Britain in the past 20 months, 12 of them since February. Coming at a time when British officials are seeking to initiate a new round of talks between Protestant unionists and predominantly Catholic nationalists in the troubled province, the attacks appear designed to remind both the authorities and the IRA's own constituents that the organization is still a force that must be reckoned with in any new political dispensation.

The underground movement has targeted soldiers and politicians in these attacks, while generally attempting to avoid harm to civilians. Ten days ago, IRA bombers blew a large hole in the first floor of the London Stock Exchange, but only after issuing eight telephone warnings to empty the building.

Last month, however, an IRA bomb injured more than 20 people at the Carlton Club, a central London landmark affilated with the Conservative Party. No warning was given before that attack.

Two soldiers also have been killed and more than two dozen injured in IRA attacks on the mainland this year.

Gow was the third Conservative member of Parliament to be killed by the IRA. Airey Neave, the party's spokesman on Northern Ireland, was killed by a car bomb in 1979. Anthony Berry died in the 1984 blast at the Grand Hotel in Brighton that was meant to kill Thatcher.