Police officers made the arrests — mostly for drunk and disorderly behaviour — in the early hours of yesterday as crowds revelled in Trafalgar Square, Whitehall, and surrounding streets.
Those arrested are aged between 18 and 44 and remain at a central London police station.
Of those arrested, eight suspects were taken into custody for being drunk and disorderly and two were arrested for assaulting officers.
Trade union members from across the UK, who had fierce battles with Thatcher in the 1980s, rubbed shoulders with those demonstrating against today’s welfare cuts.
Old and young turned out on Saturday to mark the former prime minister’s death in a celebration that was many years in the planning.
Despite the depth of feeling and a large police presence, there was no serious trouble.
A police spokesman said the last of the protesters left Trafalgar Square at about 2am yesterday and there were no reports of any damage to property.
During the protest, people drank cider and champagne, waved sparklers, and chanted slogans about Thatcher, who died at The Ritz hotel last Monday.
Members of the National Union of Mineworkers travelled to London from north-east England, Scotland, and Wales.
UK Uncut members, protesting welfare cuts, also joined the demonstration.
One protester, drinking from a mug that read “I still hate Thatcher”, said the event — initially planned by now defunct anarchist group Class War — had been years in the planning.
Fergus Ray Murray, 34, from north London, made an effigy of Thatcher from recycled materials, which was cheered as he carried it through the crowds. “It’s a chance to lay her to rest as much as possible,” he said
Former miner Dave Douglas from Newcastle, part of the delegation from the miners’ union, said Thatcher was a “terrible woman”.
“We’re absolutely furious at this image that is being presented on television, that the whole country is in mourning,” he said.
The emotion of the event was almost too much for Fred Reynolds, 80, from Sidcup, Kent, who lost his job as a Daily Express union official during Thatcher’s time in power. “She destroyed the way of life in our community,” he said.
Supporters of Margaret Thatcher are planning to enshrine her legacy through the creation of a major new institution to promote her political philosophy and shape future Conservative politics.
Plans are well under way for a Margaret Thatcher library to be built in London to stand as a lasting memorial to her achievements, it was disclosed last night.
Backers are aiming to raise £15m (€17.5m) in private funds to establish the combined library, museum, and training centre.
It is planned that visitors will be able to view key artifacts from her time in office such as her trademark blue Aquascutum suits and handbags.
The project — based on the Ronald Reagan Presidential Library and Museum in California — is said to have the backing of at least three current cabinet ministers as well as key lieutenants of the former prime minister from the 1980s.
It is being overseen by the right of centre Conservative Way Forward group established by her supporters in 1991 after she was forced out of office.
Meanwhile, the arrangements for Thatcher’s funeral on Wednesday were released at the weekend.
Her ceremonial funeral — one step down from a full state funeral, which Thatcher had said she did not want — will be held at St Paul’s, the venue for the state funerals of Lord Nelson, the Duke of Wellington, and Winston Churchill.
It was also where the Diamond Jubilee of Queen Victoria, the golden and diamond jubilees of Elizabeth II, and the wedding of Prince Charles and Diana Spencer took place.
The Queen will be among the 2,000 guests — attending the first funeral of a prime minister since that of Winston Churchill in 1965.