The fourth plinth in Trafalgar Square is to play host to a new form of popular art – hundreds of members of the public will be given their hour of fame as they each stand vigil on top of it.

The idea for the plinth, which has turned into Britain’s most prominent stage for new public art, has come from Antony Gormley, creator of the Angel of the North, who is known for using ordinary people as models for sculptures.

Gormley is one of the two names to be announced tomorrow by Boris Johnson, mayor of London, as next in line to have their works shown in the square.

Those whose ideas have lost out include Tracey Emin, who suggested displaying statues of meerkats.

Gormley’s idea is for people to stand on top of the plinth for an hour at a time and do whatever they like, within reason. “I would like the widest range of human behaviour to be represented,” said Gormley when he and five other artists were shortlisted.

Gormley, who won the Turner prize in 1994, has described the concept as “a cross between reality television and Speaker’s Corner”.He said: “It is about inviting citizens to enter the space of art and become creative partners because the 21st century is the century of the global citizen. The world is a stage and all the people must be invited to walk on it. Some may choose to remain silent; others will declaim.”

The plinth, originally intended for an equestrian statue of William IV, had been empty for more than 150 years after it was built in 1841.

In the mid1990s a plan for rotating sculptures on the plinth took off and the fourth plinth committee was established. Its members now include Ekow Eshun, artistic director of the Institute of Contemporary Arts, Grayson Perry, the potter, and Jon Snow, the broadcaster. The mayor ratifies the committee’s nomination.

The current occupant of the site is the multi-coloured Model for a Hotel, by Thomas Schütte.

The mechanism for deciding who will mount the plinth, when and how has not yet been chosen. Gormley himself has suggested that people should apply and then there will be an interview process to determine the “human sculptures”. He had originally envisaged members of the public standing there 24 hours a day.

Although the “sculptures” themselves will be cost-free, officials will have to be paid to meet health and safety concerns. Security guards will prevent pranksters or demonstrators trying to climb up.

A 12ft ladder will be erected to allow participants to get on to the plinth. It is likely that railings will also be installed to ensure they do not fall off the 16ft by 8ft platform. Back-up could be provided by a safety net and mattresses on the ground.

Frontrunners for the other sculpture include Yinka Shonibare, who wants to exhibit a model of HMS Victory in a huge bottle. The vessel was the flagship of Lord Nelson, whose column overlooks the plinth. The sculpture by Shonibare would be easier to install. In his work the fabric of Victory’s sails has been inspired by Indonesian batik designs.

Other candidates under consideration are Bob and Roberta Smith, real name Patrick Brill, whose design is an illuminated peace sign, as well as Jeremy Deller and Anish Kapoor, both former Turner prize-winners.

The replacement is likely to be put in place next year. It has not yet been decided which artist will go first but each will have about a year in pride of place.

An idea to erect a permanent statue in memory of Air Chief Marshal Sir Keith Park, one of the leaders of the RAF during the battle of Britain, has been rejected.

High art

The sculptures that have filled the vacant plinth in Trafalgar Square have been:

Ecce Homo (1999), statue of a Christlike figure by Mark Wallinger
Regardless of History (2000), tree sculpture by Bill Woodrow
Monument (2001), transparent cast of the plinth on top of the original by Rachel Whiteread
Alison Lapper Pregnant (2005), statue of naked disabled woman by Marc Quinn
Model for a Hotel (2007), brightly coloured Perspex sculpture by Thomas Schütte

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