The prospect of Lady Thatcher forever surveying the scene of the 1990 poll tax riots has been raised following calls for a statue of the former prime minister to be erected in Trafalgar Square.

On Wednesday morning the defence secretary, Philip Hammond, became the latest public figure to suggest a memorial in the capital. "I think it would be very appropriate to have a memorial to Margaret Thatcher somewhere in London," he told the BBC.

"I haven't personally given any thought yet to where that should be, but certainly the fourth plinth [in Trafalgar Square] could be one of the options."

However, Hammond urged against undue haste in putting up a statue "I think these things are better thought about in slightly slower time after the event."

A Downing Street spokesman said it was "a good idea in due course to look at how Lady Thatcher can best be commemorated". He would not be drawn on whether David Cameron was in favour of a Trafalgar Square statue or supported the campaign to rename Port Stanley, the capital of the Falklands, Port Margaret.

The fourth plinth, which has hosted works by Marc Quinn, Antony Gormley and Yinka Shonibare, is overseen by Boris Johnson, the mayor of London, who has also suggested that the city should host a significant memorial.

A Greater London Authority spokesman said: "The mayor believes Baroness Thatcher deserves a prominent statue in a central London location and his team will assist with exploring suitable options."

Former Tory minister Lord Tebbit and the Ukip leader, Nigel Farage, have added their voices to the clamour for a permanent memorial.

"I think it would be appropriate for her to be honoured publicly in the centre of London," Tebbit told the Daily Telegraph. "She could be in Trafalgar, where Nelson could keep an eye on her."

Commander John Muxworthy, a lieutenant commander on the SS Canberra during the Falklands war, is also keen to see a statue in Trafalgar Square.

"Let's have a full-scale statue next to Nelson to recognise that she was at the heart of the nation," he told the Telegraph. "It wasn't just the navy that she was a champion of; she was there for all the services. She was a great Briton, let's put her at the centre."

Farage said that while the decision to erect a statue was a "no-brainer", it ought to be located around Westminster "to show the outside world that we view her as an important political figure".

More than 100 people – among them 45 police officers – were injured on 31 March 1990 after an anti-poll-tax rally in central London turned violent. The much-hated tax, and the scenes of disorder in Trafalgar Square that day, helped to bring Thatcher's premiership to an end.