Back in 1994, when the businesswoman, restaurateur and RSA chair Prue Leith wrote in the Evening Standard that the long vacant fourth plinth in Trafalgar square should be filled by public suggestion, her proposal was met with consternation. Some saw it as an act of “meddlesome pointlessness”. The vacant 16 by 8 foot mount in Trafalgar’s northwest corner had stood vacant for almost 150 years. Why bother with it now? Leith wrangled her way through a bureaucratic swamp that included negotiations with the Victorian Society, the Georgian Society, the Fine Arts Commission, the English Heritage, the Westminster Public Art Advisory Committee and the Armed Forces a number of others to gain permission to put contemporary art on the plinth. Along with the way – advised by a special report considering both public and critical opinion – it was decided that the Fourth Plinth (now with a capital “FP”) would become a site for temporary contemporary art: a rotating platform for newly commissioned work to be decided upon, in part, by the public.

It took five years to bring the plan to fruition, but in 1999 Mark Wallinger unveiled Ecce Homo, a life-sized sculpture of Christ that commented quietly on the bravado of outsized statutes nearby. A year later, Bill Woodrow’s Regardless of History surmounted the space - a bronze bust bound to the plinth by the roots of a dead tree. Next came Rachel Whiteread’s understated Monument: a replica of the Plinth cast in clear resin, inverted, and plonked on top of the original. She called it “a pause in the city, a place that felt very quiet.”

Year on year, the Plinth has serves as receptacle for the latest in a line of noted contemporary works that has included, most famously, Mark Quinn’s mammoth marble statue of disabled mother Allison Lapper and Antony Gormly’s Plinth-as-stage live art marathon One & Other. This week the Institute of Contemporary Arts opens what could be called the Plinth’s first retrospective -  Fourth Plinth: Contemporary Monument. It’s essentially a chronological walk through of each of the Plinth commissions, including several notable entries that only just missed sitting on the spot. There’s a scale maquette of each of the works, from Sarah Lucas’s pigeon-shit stained saloon car to Bob & Roberta Smith’s Make Art, Not War – a towering carnivalesque construction that, if realised, would have reached as high as Nelson’s column. The gallery space is dramatically lit, lending the miniatures a sense of ceremony fit for the crown jewels. It’s a reverential touch, but is all the reverence justified?

The show shies not away from the controversy the Plinth has courted over the years. At the centre of the exhibit sits another chronological presentation – this time it’s four walls of news clippings from the mid-1990s onwards, documenting press and public reaction at various stages. Critical denunciation comes from various voices including writer/broadcaster Mathew Collings and the former deputy leader of the Labour Party, Roy Hattersley, who called the Marc Quinn piece “the wrong statue in the wrong place” and suggested a permanent tribute to William Shakespeare in its stead. The ever vocal Jonathan Jones, four years back, compared the Plinth unfavorably to its 19th-century counterparts, calling it “a staid and boring institution… a manifestly pompous way of giving weak sculpture a bit of authority”.

On the other side there is gushing praise. In one glowing review, the Standard’s Ben Lewis praises Anthony Gormley for creating “public art work that the public like”:

There is one thing I really admire about Gormley’s Fourth Plinth. Predictable, unoriginal, and boring as it is, this is a work of art that is so politically correct it’s impossible to criticise it without sound like a fascist.

It’s a sentiment that could apply to the Plinth as a whole – it has always had the public’s best interests at heart, and it’s hard to criticise it without sounding like a grumpy old scrooge. As trendy or pointless as some of the commissions may have been, the project's aim from its inception has been to promote art, not for the glory of the artist, but for the sake of the people. As Sally Shaw, head of culture for the Mayor of London, tells me, the public have in fact been a major factor in selecting commissions over the past decade. Responsibility for the Plinth was handed over from the RSA to the Mayor of London in 2003. The programme went briefly underground before remerging in the format we now know today. This, she says, is a “rigorous process that takes a good deal of time”:

We draw up a long list of 150 artists, and from there we will usually contact forty people and ask them if they’d like to submit a proposal. The Mayor’s Culture Team works with the Fourth Plinth Commissioning Group [a body formed of members from the Arts Council, journalists, curators, and artists including Jeremy Deller and Grayson Perry] and from there we whittle it down to six final commissions, which we then submit to the public for commentary.

This process of “commentary” is no after-thought, but rather an active exhibition staged over a period of months where visitors are encouraged to comment and vote for what they’d like to see put up next. The last show drew 17,000 comments. Shaw and her team sift through them all as part of an effort to make the Fourth Plinth “the most open and public commissioning programme for contemporary art”.

“The Plinth gets people talking about art,” she says with a grin. “Contemporary art can often be seen as elitist, or we talk about it in too complicated a way. It’s unfortunate but true. But the public talk so easily about what’s on the Plinth, it gets people thinking about difficult ideas, talking about fantastic subjects. Its temporary nature makes it significant as a piece of London’s changing geography, tracking cultural responses to political issues and contemporary history. Each piece says something different about the city and the people who put it there.”

So how long can the project run? Can the “permanent programme for impermanent art” formula succeed long term? ICA Director Gregor Muir chimes in: “The project really belongs to everyone; its audience is in the millions.

“The public are now part of the equation,” he adds. “It has grown off the public reaction, getting everyone involved, and moving contemporary art forward. I can’t see it going away now that it’s at the heart of this city.”

Grayson Perry, who is wandering nearby, is cackling approvingly about the Plinth’s longevity. I overhear him saying that he is particularly excited about the big blue cock due to go up this July.

Fourth Plinth: Contemporary Monument runs until 20 January 2013 at the ICA, London SW1. [2]

(Marc Quinn, Alison Lapper Pregnant, 2003. PHOTO: James O’Jenkins/ICA)

(Installation View. PHOTO: James O’Jenkins/ICA)

(Installation View. PHOTO: James O’Jenkins/ICA)

(Yinka Shonibare, MBE, Nelson’s Ship in a Bottle, 2008. James O’Jenkins/ICA)

(Katharina Fritsch, Hahn / Cock, 2010. PHOTO: Oli Scarff/Getty Images)

(Thomas Schutte, Model for a Hotel, 2007. PHOTO: James O’Jenkins/ICA)

(Installation View. PHOTO: James O’Jenkins/ICA)