Ex-Tory deputy chairman and genuine eccentric

Alistair McAlpine, who has died aged 71, was a man of extraordinary individuality: his life was a succession of transient passions. At various times he was a political campaigner and adviser, a pearl farmer, a country gentleman, a builder, a shopkeeper, an antique dealer, a journalist and author and the proprietor of an Italian bed and breakfast operation. He was a true eccentric in the finest tradition of the maverick.

The great-grandson of “Concrete Bob”, the founder of the McAlpine building company, he was born at the Dorchester hotel in London, where his baby milk was delivered by room service.

Margaret Thatcher appointed him as honorary treasurer, a post he occupied from 1975 to 1990. He was also deputy chairman of the party from 1979 to 1983. Having raised many millions to fight the 1979 and 1983 elections, he was rewarded with a life peerage in 1984.

A man of with a great sense of fun and mischief, he claimed to have helped secure Thatcher’s continuation as prime minister in 1983 by buying up all available copies of Labour’s radical manifesto – dubbed by Labour MP Gerald Kaufman “the longest suicide note in history” – to Tory supporters in business and the City in an operation that he claimed was so successful he had no need to commission any further advertising, thus saving hugely on the party’s election budget.

He was most recently in the news when he was wrongly identified on Twitter in 2012 as the Conservative politician from the Thatcher era mentioned anonymously on a BBC Newsnight programme as having been involved in allegations of the sexual abuse of boys. He was profoundly hurt by the suggestion and as a result of legal action was awarded apologies and considerable damages in consequence, including £185,000 from the BBC and £15,000 from both the comedian Alan Davies and Sally Bercow, the wife of House of Commons Speaker John Bercow. The money was donated to charity but did not assuage the offence caused him by the casual cruelty of the internet.

Alistair McAlpine was the third of four children of Edwin McAlpine, Lord McAlpine of Moffat, and his wife, Mollie. He was educated at Stowe school, Buckinghamshire, which he left at 16 to begin work as a builder. His father had sent him weekly copies of a magazine called The Muck Shifter to prepare him for a life in industry. At the age of 21 he became a director.

Luxurious life
In his autobiography he acknowledged that his life as a child was a luxurious one and it did not change much thereafter. He started working in Australia in the 60s, developing a luxury resort at Cable Beach, Western Australia. He also started a parrot collection, opened a zoo and began pearl farming. His collection of modern art and sculpture, some of it later gifted to the Tate Gallery, was impressive.

It was when he met Thatcher that he found his passion for politics, which lasted probably longer than most of his enthusiasms. Though not a conventional Conservative, he was stimulated by the fun element of the political life.

Political salon
Fuelled by copious quantities of the best champagne, he set about helping improve the new party leader's personal reputation with everyone who he thought mattered, from the most distinguished dignitaries to those at the rougher end of Fleet Street. He established a political salon in Central Office, bought a Georgian town house across the road from the House of Lords for entertainment purposes and was the first to host late-night lobster and champagne parties at party conferences to sweeten political opinion.

A brilliant and generous host in London, Venice, Perth, Monaco and Puglia, he was loyal to those he counted as his friends, irrespective of their status, wealth or politics. In particular he remained a devoted friend to Thatcher. He was outraged by the manner of her fall from power, and having become increasingly sceptical about Europe joined the Referendum party, formed by Sir James Goldsmith, in 1996. The following year Goldsmith died, and McAlpine succeeded him as leader. In recent years he rejoined the Conservatives.

He survived attacks by the IRA twice, first at Brighton in 1984 and then again in 1990 when the IRA bombed West Green House, a 17th-century Hampshire mansion in which he lived as a tenant of the National Trust. Knowing that his name was on a Republican hit list he had moved his family to Italy shortly beforehand.

At West Green, McAlpine restored the gardens and the house. Among a number of follies was a triumphal arch in honour of Thatcher and a 50ft column with an inscription in Latin celebrating the fact that the money spent on it had not instead gone to the Treasury.

In Venice, he bought a small castello behind the Arsenale. He would meet guests at the airport dressed in a black coat and broad-brimmed hat in the style of an earlier Venetian resident, Frederick Rolfe, "Baron Corvo", the author of Hadrian the Seventh.

He gave an account of his work for Thatcher in a reworking of Machiavelli's The Prince called The Servant. He also wrote a successful book of memoirs, Once a Jolly Bagman. He was an avid collector of many things, from fine art to snowdrops, police truncheons to African beads.

He is survived by his third wife, Athena (Malpas), and three daughters, two from his first marriage and one from his second.