Built in 1841, the fourth plinth in Trafalgar Square is unique. It is for an equestrian statue that was never completed, and was left unadorned for decades, in one of the world's most iconic public squares. But such an artistic vacuum had to be filled and generations later in 1998, the RSA commissioned three temporary works on the plinth, to raise awareness of public art.

These were so popular that a specially convened government committee recommended that the plinth be used for a rolling series of temporary works. The proposal was adopted by the Mayor of London in 1999 and the Fourth Plinth Commissioning Group was born. The void had been filled.

Comprising the great and good of the art world, the group commissions art that attracts significant public interest, and often generates voluble criticism and praise in equal measure. In recent years, we have seen Marc Quinn's Alison Lapper Pregnant and Thomas Schütte's Model for a Hotel, two cases in point: most people loved or hated them. Debate raged in newspapers and the back of cabs.

This level of controversy is exactly what the commissioning group hoped for. After all, the second aim for the fourth plinth project is to “act as a focal point for a wider public debate on public art, urban design and civic space”.

Times Archive, 1940: 650 aircraft driven back

The leader of a Spitfire squadron broke up the largest formation of Messerschmitt fighters the British pilots had ever seen

• Big battle near London

BACKGROUND

• They were the Few - but Park was a one-off

• 'If I take my hands off the controls . . .'

• Revenue looks for new broom

• Et in Orcadia ego: confessions of a D & D addict

After Schütte, two more works loom on the horizon. First up will be Antony Gormley's One and Other, in which the plinth will be occupied for an hour at a time by thousands of ordinary citizens over 100 days. Then Yinka Shonibare's Nelson's Ship in a Bottle, with sails made from patterned textiles associated with Africa.

Then a wild card has been thrown into the mix. An application has been submitted to Westminster City Council (which decides whether a commission goes ahead) for a large statue of the Battle of Britain hero Sir Keith Park to have a six-month residency on the plinth, before the installation of a smaller permanent bronze statue in Waterloo Place next year.

The application, by the Sir Keith Park Memorial Campaign, is for a figurative statue by the sculptor Les Johnson. The campaign has the support of Boris Johnson, the Mayor of London, other VIPs, veterans, the Park family and most importantly, countless thousands of members of the public.

The council's decision, which is likely to come tomorrow, will in all likelihood prompt more debate about what is appropriate art for the plinth, and this is precisely what the art establishment should welcome. The timing is ideal. This installation will ensure that the art establishment engages in the debate about whether traditional figurative statues can be considered public art.

With the approaching 70th anniversary of the Battle of Britain, fought above Trafalgar Square, London and the South East, this would be an excellent way of showing that London has not forgotten one of its heroes - with the bonus, in this time of austerity, that the taxpayer will not pay a penny for this installation, unlike previous exhibits.

There is a danger that this could descend into a predictable and scripted bout of name-calling based on entrenched positions about “modern” versus “traditional” art. But a spat between those from different ends of the art spectrum is entirely unnecessary - when one considers the brief that artists on the list drawn up by the commissioning group were expected to follow, the Park statue fits the bill perfectly.

Counterintuitively, by being a traditional figurative sculpture, the statue will push back boundaries and challenge what has become the received wisdom: that traditional art forms do not command as much respect in the contemporary art world, not least on the fourth plinth.

That aside, when one compares the Park statue with the artist's brief, it holds up extremely well. There is no doubt that it will be “of the highest quality”: Johnson is a world-renowned sculptor. In speaking to a hugely important chapter in our history - the sacrifices made on our behalf in the Second World War - it surely promotes Trafalgar Square “as a public space for cultural and social engagement” in a profound and important way. Given that Park was responsible for the fighter squadrons that defended London and the South East, it certainly refers to the “conceptual, historical or formal framework of the square as a central public space for London”.

And given that Park's leadership is widely believed to have been crucial to our victory in the Battle of Britain, itself of huge significance in the result of the Second World War, it is obvious that the statue relates well to the “national and international significance” of the square. It is true that the brief states that a commission “need not necessarily be a work of object-based sculpture”, but it does not rule this out either.

If placed on the fourth plinth in between Gormley and Shonibare's work, a statue of Park would take its place among the panoply of different styles that make up modern art in its broadest sense. Gormley seeks to democratise the plinth, to allow ordinary individuals to express themselves for an hour, in any way they see fit. Shonibare hopes that he will be “giving expression to and honouring the many cultures and ethnicities that are still breathing precious wind into the sails of the UK”.

The Park statue will extend both these themes by reminding all who view it that freedoms, including artistic ones, were hard-won by those such as Park and the countless thousands who served alongside him.

They will be reminded too that a multitude of people of all races, from throughout the Commonwealth and all corners of the globe, fought with Britain against tyranny, in defence of freedom. As an art installation, the statue will push back the boundaries of what contemporary art can achieve and what public art is for.

There could be no better way to stimulate debate on urban design, public art and civic space than by a statue of Sir Keith Park, nicknamed by the Germans in 1940 as “the Defender of London”, being erected on the fourth plinth 70 years on.

William Packer is an artist and former art critic of the Financial Times. Frederick Forsyth is a bestselling novelist

Times Recommends

• Ted Hughes was a prophet of climate change
• Health & safety can damage your reasoning
• It’s Big Brother’s stupidity that scares me