Why are we asking this now?
The Barracks is a dream site for any developer who might be a descendent of Croesus, the fabulously wealthy king of Lydia, circa 550BC. The site covers more than five hectares of one of London's fanciest sites, close to the river and directly opposite Wren's Royal Hospital. In the Croesus stakes, few families are wealthier than the royal clan of Qatar, one of whose companies, Qatari Diar, bought the Barracks jointly with CPC Group, operated by the Candy brothers, for £950m last year. Prince Charles dislikes their scheme for the site, designed by Lord Rogers' practice, Rogers Stirk Harbour, and has apparently quilled a note to Qatar's rulers, asking them to use another architect.
What will the scheme provide?
Its 552 housing units will be a 50/50 mix of affordable and market-priced properties. The cost of the latter, in so-called "garden pavilions", will be stratospheric. Significantly, the scheme is of lower density than Rogers' original offering, following critical public feedback during Westminster Council's consultation process. The affordable housing has been designed by Alford Hall Monaghan Morris, and the considerable public space element by Heatherwick Studio, whose principal, Thomas Heatherwick, is even politer than the architecture-sensitive popular philosopher Alain de Botton, but gives great wow factor.
Why are people fretting about it?
The Rogers' scheme goes to Westminster Council's planning committee in June. Prince Charles complains about modern architecture regularly, and it's very tempting to dismiss his Qatari communiqué – reported as "a private letter that may or may not have been sent" – as an equivalent of hearing the first cuckoo in the spring. Unfortunately, the issue is of profounder import, and can be summed up in one question: is Prince Charles in charge of Britain's planning system? This brouhaha is not simply fallout from his latest, no doubt well-meant, assault on urban change: it is about the apparent stealth and influence of his intervention.
What's controversial about the development?
Its size, and the relationship of its 21st-century architecture to the streets and buildings around it. The scheme is London's poshest big development at £70m an acre, and Wren's baroque Royal Hospital is no more than two or three spitting dowagers away. An earlier version of the proposal, also by Rogers, was turned down by Westminster, who know this scheme will re-set the bar for big up-scale regeneration. The council's nervousness has been notable: Rogers' original design was hardly luridly avant garde, and nor were other schemes offered by architects such as John McAslan + Partners, and Michel Mossesian.
How important is the project both architecturally and for London?
Britain's planning system, and absurdly constipated mechanisms such as PFI building schemes, are hardly ideal. Until recently, the rush to build – and the threat of costly appeals by developers – too often forces councils to wave through architecturally rotten projects. In London, it seems only high-profile schemes get microscopic examination, with favour shown towards the iconic, particularly in the Square Mile. But it is non-iconic developments that need more care and attention. The current Chelsea Barracks scheme is, strangely enough, in the latter category. But how many other housing schemes will Westminster examine with such care?
What would Prince Charles prefer to see?
Something faux historic, perhaps by Quinlan Terry, one of his personally approved architects. Terry has a profound understanding of the manner of classical architecture, and his architectural garlands include the Philippe Rothier Prize, the Georgian Group's 2003 Best Modern Classical House award, and a Riba Building of the Year award for the library at Downing College, Cambridge. If Terry's architectural manners are impeccable, his ability to turn manners into contemporary architectural meaning is questionable. Even the classically inclined Alain de Botton (see "polite", above) has dissed his architecture.
How does Lord Rogers compare?
Richard Rogers is a modernist, an urbanist, and one of the world's most famous designers. His breakthrough came when, as unknowns, he and Renzo Piano won the competition to design the Pompidou Centre in Paris – an innovative "fun palace" structure that made them famous in 1977. His Lloyds building in London was a brilliant and strangely gothic altar to profitable disaster, and his practice's buildings invariably exhibit bravura structures – none more so than Madrid's Barajas airport. Rogers' lead architect for the Chelsea scheme is Graham Stirk, the practice's main injector of design elegance.
We've been here before haven't we?
Indeed. Prince Charles' interest in architecture is, without doubt, admirable. And we must be grateful that he has inadvertently shared his thoughts on this crucial subject with us – as if we were almost on the same footing as the Qatari royal family. The Prince of Wales burst on to the architectural radar in the 1980s, when he effectively torpedoed Richard Rogers' design for the extension of the National Gallery as a "monstrous carbuncle", and then blocked the same architect's project for Paternoster Square. Prince Charles' subsequent creation of the Poundbury model village in Dorset showed that he was ready to rock, but only in the neo-vernacular mosh-pit.
Is Prince Charles cruising for a bruising?
Well, the architectural cavalry have certainly arrived at Lord Rogers' putative Alamo. Eight of the profession's heavy mob, including Lord Foster, Zaha Hadid, Jacques Herzog, Jean Nouvel, Renzo Piano and Frank Gehry have signed a letter of complaint about the royal intervention. They object, righteously and with understandable future self-interest, to the possibility of London planners being influenced in this particular way. How strange that Prince Charles didn't simply mount a public attack on the Rogers scheme: a much more thorough, and interesting, debate would surely have ensued.
Who's going to win?
It seems inconceivable that Westminster Council would be deflected by what gives every impression of being a strangely skulking blind-side architectural run by the heir to the throne. We cannot assume that the Rogers scheme is necessarily a perfect answer to the challenge of the Chelsea Barracks site; but it has been through Westminster's planning mill. Neither they, nor Lord Rogers, can know how well the development might contribute to Chelsea in 30 years' time; at its best, architecture is an art, and a civil act of faith. It's about developers making money, too. In a public setting, it should never be about a singular obsession that casts doubt on public processes.
Is the Prince right to intervene?
*He speaks for a majority who oppose modernist architecture
*He is right that this site, next to Wren's Royal Hospital, needs a more compatible building alongside it if its own virtues are to be retained
*He has spoken out before on architecture and has every right to exert his influence
*In appealing to the site's owners, he is abusing his privileged position
*He is circumventing the planning procedures, which is where public objection should properly be heard
*His objections are based on a nostalgic preference for traditional architecture that would hamper the work of modern practitioners