Why Margaret Thatcher regretted going into politics

Margaret Thatcher confided to a prominent Conservative MP that she would not have gone into politics if she "had her time over again" because of what it had done to her family, a new book reveals.

The startling admission is contained in a set of diaries by Sir Michael Spicer, a Tory grandee, which begins its serialisation in The Sunday Telegraph today.

The book gives an insider's view of the Thatcher years, including the Falklands Conflict, the Brighton bomb and her acrimonious departure in 1990.

Sir Michael, a former minister and party official who left Parliament at the 2010 election, also provides a vivid portrayal of the bitter struggle over the Maastricht Treaty, which split the Conservatives and brought John Major's government to its knees in the 1990s, as well as the fall of Iain Duncan Smith as Tory leader and the rise of David Cameron.

Lady Thatcher, Sir Michael writes, became disillusioned after stepping down as prime minister in November 1990, telling him in the Commons in February 1991: "I hate coming to this place now."

Her confession that she would not have chosen a political career in retrospect, depriving Britain of arguably its greatest peacetime prime minister, came in April 1995.

That was shortly before Major's resignation and re-election as Tory leader, following years of warfare with the Right wing of his party, which sought to use his predecessor as a "rallying point", according to The Spicer Diaries.

In a meeting with Sir Michael in her office in Chelsea, with her husband, Sir Denis present, she told him: "If I had my time again, I wouldn't go into politics because of what it does to your family."

Throughout her time in office, and afterwards, Lady Thatcher was loyally supported by Sir Denis, who died in 2003. However, her son, Sir Mark, won a reputation as playboy, at one point in her premiership going missing for six days during the Paris-Dakar rally. His twin sister, Carol, is a journalist who appeared on I'm A Celebrity, Get Me Out of Here, the television reality show, in 2005.

Despite her mother's mental decline, Carol can go for months without visiting, according to reports, and Sir Mark lives in Spain, coming to London to see her roughly once every four to six weeks.

The former prime minister's two grandchildren live in Texas where Sir Mark's former wife, Diane, is based.

The Spicer Diaries also detail the Commons expenses scandal of 2009 exposed by The Telegraph, in which Sir Michael was accused of using taxpayer's money to maintain a "helipad" at his Worcestershire home - a claim he denies.