9 November 2012 Last updated at 09:25 ET

Profile: Lord McAlpine

Lord McAlpine was among Lady Thatcher's closest friends and advisers

As a member of a famous construction dynasty, Alistair McAlpine had a household name from birth.

His grandfather Sir Robert, known affectionately as "Concrete Bob", founded the firm, which remains one of the biggest builders in the UK, responsible for the London 2012 Olympic stadium among many other projects.

But Alistair, now 70, has blazed a long and impressive trail of his own in public life - as an art collector, property developer, author, fund raiser and loyal political servant to Margaret Thatcher.

Known as a jovial, cultured character, with a love of modern art, he was at one time one of the most powerful figures in the Conservative Party.

He was made a director of the family firm at 21, five years after dropping out of top public school Stowe, with three O-levels.

He went on to make a fortune of his own as a property developer in Australia, before discovering his political vocation at a dinner party in 1975.

'Moral duty'

That was when he first met Margaret Thatcher, recently elected leader of the Conservative Party.

He became one of her closest and most devoted advisers and Conservative Party treasurer throughout her period in office, from 1979 to 1990.

She made him a life peer, Baron McAlpine of West Green in Hampshire, in 1984.

He is remembered as perhaps the most effective political fund raiser of his generation, helping to bankroll three successful general election campaigns.

But he also faced controversy after accepting donations from disgraced tycoon Asil Nadir's Polly Peck firm.

In August this year, he told the Daily Mail the Conservative Party should return the money - a call that has so far gone unheeded.

"It is tainted money and it shames the Conservatives if they hang on to it. They have a moral duty to give it back," said the peer.

In parallel to his political career, Lord McAlpine became a leading art collector and gallery owner, with an interest in artists such as Mark Rothko, Morris Louis and Jackson Pollock.

Slow down

The peer took Lady Thatcher's rejection by her MPs in 1990 hard, remaining loyal to her in the difficult years that followed her departure from Downing Street and funding her private office.

The dedication of his book The Servant - an update of Machiavelli's The Prince - says: "To the most magnificent, Baroness Thatcher of Kesteven, Prime Minister of Great Britain 1979- 1990, from one of her many Servants, who believes she could have been better served."

Lord McAlpine - pictured here in 1998 - was a skilled political fund raiser

He turned his back on the Conservative Party at the 1997 general election, campaigning for Sir James Goldsmith's eurosceptic Referendum Party, although he returned to the fold some years later.

In recent years, he has largely disappeared from public life, opening a bed-and-breakfast in an old monastery in Puglia, Southern Italy with his third wife.

He has not sat in the House of Lords since rules on non-domiciled tax changed in 2010.

He was known for his fast-paced, convivial lifestyle but was forced to slow down, and stop smoking, in 1987, after a seven hour heart bypass operation, complications from which led to him having a tracheotomy and difficulty speaking.

He has three children, two from his first wife.

On Friday, he issued a statement categorically denying claims he was involved in child abuse at a Wrexham children's home, after being named on the internet and by implication by other media.

Lord McAlpine said that, in doing so, he had not given up his right to sue those who had defamed him and he would take all steps considered necessary to protect his interests.

His denial comes after Steve Messham claimed on the BBC's Newsnight that he had been abused by a senior politician of the Thatcher era, who was not named, at the Bryn Estyn children's home.

The claims are "wholly false and seriously defamatory", the Conservative peer has said.