Boris Johnson has hailed Margaret Thatcher as a “true feminist, green and revolutionary” who was fighting global warming long before the “nose-ringed, hemp-smelling” Extinction Rebellion "crusties" currently occupying the streets of Westminster.

The prime minister said his predecessor at 10 Downing Street was taking climate change seriously “long before Greta Thunberg” and was “right” about issues ranging from the EU and the euro to council tax, the "loony left" and apartheid.

And he branded as “regicides” the Conservative MPs who forced her out of office in 1990 amid a row over the EU, paving the way for the more europhile John Major to take her place.

Speaking at the launch in Whitehall’s Banqueting House of the third volume of Charles Moore’s official biography of Thatcher, Mr Johnson also controversially claimed that the former PM had “secret dealings with Nelson Mandela and the ANC to bring about Mandela’s release and the end of apartheid”.

During her time in office, Mrs Thatcher was widely condemned for her opposition to sanctions on the racist apartheid regime in South Africa and her description of Mandela’s ANC as “terrorists”. But after her death, aides including the former UK ambassador to Pretoria revealed she had privately pressed president PW Botha to free Mandela and end apartheid.

Mr Johnson said that to get to the launch, he had to brave the streets filled with "unco-operative crusties and protestors of all kinds" taking part in the Extinction Rebellion action to demand more decisive action against climate change.

Margaret Thatcher: Life in pictures Show all 35 1 /35 Margaret Thatcher: Life in pictures Margaret Thatcher: Life in pictures 403788.bin We are a political grandmother: Margaret Thatcher as prime minister, 1 August 1980 Getty Images Margaret Thatcher: Life in pictures 191385.bin Margaret Thatcher: Life in pictures 191386.bin Margaret Thatcher: Life in pictures 191387.bin Margaret Thatcher: Life in pictures 192809.bin Margaret Thatcher: Life in pictures 168685.bin Margaret Thatcher: Life in pictures 168686.bin Margaret Thatcher: Life in pictures 192808.bin Margaret Thatcher: Life in pictures 168688.bin 1 June 1979: Prime Minister Thatcher sits with her new Cabinet at No 10 Downing Street. Left to right (standing): - Norman Fowler, Transport Minister; John Biffen, Chief Secretary to the Treasury; David Howell, Energy Secretary; Norman St John Stevas, Chancellor of the Duchy of Lancaster; Humphrey Atkins, Northern Ireland Secretary; George Younger, Scottish Secretary; Michael Heseltine, Environment Secretary; Nicholas Edwards, Welsh Secretary; Patrick Jenkin, Social Services Secretary; John Nott, Trade Secretary; Mark Carlisle, Education Secretary; Angus Maude, Paymaster General; and Sir John Hunt, Secretary to the Cabinet. Left to right (seated) :- Sir Ian Gilmour, Lord Privy Seal; Lord Soames (1920 - 1987), Lord President of the Council; Sir Keith Joseph, Industry Secretary; Lord Carrington, Foreign Secretary and Overseas Development; William Whitelaw, Home Secretary; Margaret Thatcher, Prime Minister; Lord Hailsham, Lord Chancellor; Sir Geoffrey Howe, Chancellor of the Exchequer; Francis Pym, Defence Minister; James Prior, Employment Secretary; and Peter Walker, Agriculture Minister. Getty Images Margaret Thatcher: Life in pictures 285241.bin On becoming Prime Minister in May 1979, Margaret Thatcher sought ways to cut spending Getty Images Margaret Thatcher: Life in pictures 168691.bin Margaret Thatcher: Life in pictures 50419.bin Emlyn Hughes (R) and Kevin Keegan (L) enjoy a joke with Mrs Margaret Thatcher outside No 10 Downing Street in 1980 Getty Images Margaret Thatcher: Life in pictures 168690.bin 1 January 1980: Margaret Thatcher with Chairman of the Conservative Party Lord Peter Thorneycroft (left) at the party conference in Brighton Keystone/Hulton Archive/Getty Images Margaret Thatcher: Life in pictures 168700.bin 4 November 1981: The Prime Minister with Geoffrey Howe, Keith Joseph, John Nott, Norman Tebbit on the Conservative front bench in the House of Commons. Central Press/Getty Images Margaret Thatcher: Life in pictures 192781.bin Margaret Thatcher: Life in pictures 168702.bin 22 March 1982: Thatcher with Indian premier Indira Gandhi outside 10 Downing Street. Central Press/Getty Images Margaret Thatcher: Life in pictures 168701.bin Margaret Thatcher: Life in pictures 191388.bin 1984. British Prime Minister Margaret Thatcher shares a joke with American President Ronald Reagan, at No. 10 Downing Street, London. Getty Images Margaret Thatcher: Life in pictures 168704.bin 12 October 1984: The devastation caused by an IRA bomb at the Grand Hotel in Brighton, where Margaret Thatcher and her ministers were staying for the 1984 Conservative Party Conference David Wimsett/Getty Images Margaret Thatcher: Life in pictures 168706.bin 1 January 1985: Margaret Thatcher with a chimpanzee Keystone/Getty Images Margaret Thatcher: Life in pictures 192805.bin British Prime Minister Margaret Thatcher dances with US President Ronald Reagan 16 November 1988 following a state dinner given in her honor at the White House. Getty Images Margaret Thatcher: Life in pictures 168708.bin 1 Fwbruary 1985: Four of the voice artists on the satirical TV programme, 'Spitting Image' with some of the puppets, for which they provide voices (Margaret Thatcher, Robin Day, Vincent Price and Prince Philip). Back, left to right: Chris Barrie, Jon Glover, Enn Reitel. Front: Steve Nallon. Express/Express/Getty Images Margaret Thatcher: Life in pictures 163488.bin Margaret Thatcher looks pensive at the Conservative Party Conference, October 1985 Getty Images Margaret Thatcher: Life in pictures 168711.bin Margaret Thatcher: Life in pictures 110601.bin Margaret Thatcher: Life in pictures 192807.bin Margaret Thatcher: Life in pictures 111403.bin Margaret Thatcher, then Prime Minister, famously posed at the wheel of a Nissan Bluebird PA Margaret Thatcher: Life in pictures 140162.bin Out of action: when the miners' strikes failed to budge Margaret Thatcher, it spelt the end of union power PA Margaret Thatcher: Life in pictures 167141.bin The big picture

The poll-tax protest turns ugly

1 April 1990 On the afternoon of Saturday 31 March, a peaceful protest against Margaret Thatcher's unpopular poll tax turned to violence in the centre of London. This picture by Jon Jones, which we ran on page two, was probably stronger than the one we ran on the front page, which showed some of the damage caused by the riot. Robust police behaviour attracted less controversy back then than it did during the recent G20 protests in the City of London. Jon Jones Margaret Thatcher: Life in pictures 33728.bin Baroness Margaret Thatcher Chris Jackson/Getty Margaret Thatcher: Life in pictures 30501.bin Margaret Thatcher: Life in pictures 48234.bin Carol Thatcher and her mother, the former prime minister, who suffers from dementia and often forgets recent events REUTERS Margaret Thatcher: Life in pictures 52821.bin Baroness Thatcher and Tony Blair stand beside Gordon Brown AP Margaret Thatcher: Life in pictures thatcher_2.jpg Margaret Thatcher: Life in pictures thatcher-2_1.jpg Getty Images

He told his audience: “I hope that when we go out from this place tonight and we are waylaid by importunate nose-ringed climate change protestors we remind them that she was right about greenhouse gases

“And she took it seriously long before Greta Thunberg.

“ And the best thing possible for the education of the denizens of the heaving hemp-smelling bivouacs that now litter Trafalgar Square and Hyde Park would be for them to stop blocking the traffic and buy a copy of Charles’s magnificent book so that they can learn about a true feminist, green and revolutionary who changed the world for the better.”

Mr Johnson described Thatcher’s removal from office in 1990 as “a single glittering and terrible event. An assassination The political extinction of a long serving monarch.”

And he borrowed from Mark Antony’s damning description of the murderers of Julius Caesar as “honourable men” in Shakespeare’s tragedy to suggest his own disdain for those who brought about her downfall.

Extinction Rebellion protest in Westminster (PA)

“Just like Julius Caesar this drama raises in all our mind the question ‘Were they right? Were the regicides justified in what they did?’” said Mr Johnson