Why should anyone assume that new architecture and old music cannot be compatible?

The Coliseum is an oddball building in London's St Martin's Lane leading down to Trafalgar Square. It was designed by Frank Matcham (Hackney Empire, London Hippodrome, Victoria Palace) in a showbiz Baroque style, borrowing a little from Wren's Royal Naval Hospital, Greenwich, and opened as a music hall in 1904. It is not a particularly fine building, but like all Matcham's designs it is warm, engaging and rather lovable.

Since 1968 it has been home to the English National Opera, and from 1992 the opera company has owned the freehold thanks to the largesse of that musical ex-minister, Dave "Chelsea" Mellor. Now the ENO wants to move to a new home, paid for with Lottery funds (or so it hopes) and possibly sited at King's Cross, Bankside or the Hungerford car park.

ENO has good reasons to move from the Coliseum: the building is in rickety shape; it is too cramped and lacks the sort of modern facilities that would allow it to put on co-productions with better equipped companies elsewhere in Britain and abroad. Last season it had to turn down a David Hockney-designed Turandot from Los Angeles because of its backstage inadequacies. Such co-productions are essential for under-funded opera companies. To earn its keep, ENO needs to run a major and a minor production concurrently; it cannot do this within the wobbly Edwardian confines of the Coliseum.

Yet, although the case for a brand-new opera house is sound, ENO's plans have been attacked left, right and centre. Look, say a chorus of critics this week, at the horrid new opera house at the Bastille in Paris: the grim building is already showing signs of premature senility. Who wants to go there when Garnier's lovely old opera house stands but a mile away?

And who, in their right mind, would traipse all the way to Kings Cross, legendary land of strip-tease, hoody pimps, budget tarts and drug-dealers, to sit through an opera in English anyway?

First things first. The Coliseum would be a much happier building if bought by Lord Lloyd Webber or Sir Cameron Mackintosh, say, and turned back - and forward, as it were - into a home for just the sort of light musical entertainment it was originally designed for (with revolving illuminated disco globe on top).

The ENO, removed from Trafalgar Square, would not be going to the cultural equivalent of the North Pole. Bankside is already home to the Globe and soon to be home to the new Tate; the Hungerford "car park" is bang next to the South Bank and soon to become part of Lord Rogers' Thames-side "string of pearls" - hardly cultural wildernesses. As for Kings Cross, it will develop into a vibrant quarter soon enough: an opera house would only help it along.

In any case, why should anyone assume that new architecture and old music cannot be compatible? New concert halls have thrived, even when their locations have seemed less than auspicious: consider the success of those built recently in Birmingham, Manchester and Glasgow, acoustic triumphs all. Think, too, of Michael Hopkins's new, enlarged Glyndebourne Festival Theatre and of the Jeremiahs who doomed it to failure: take away its "village hall" character and that would be the end of it. In fact, Glyndebourne, an out of the way place for an opera house, has never been more popular.

In the world of pop, Wembley and Birmingham Arenas, neither located in desirable or even remotely likeable places, are often packed to their gunwhales. There is no reason why an inventive and catholic programme of operas put on in a glamorous new building in Kings Cross, Bankside or wherever, will not succeed.

Several of ENO's fiercest critics appear to believe that districts like these are no-go areas set in the fifth dimension, which is nonsense. London is not, as some fashionable writers like to believe, a cosy medley of old-time villages, but a writhing, snaking, energetic and creative capital - big-scale, small-scale, old and new - that moves and shakes, sometimes displacing old and much loved institutions into new homes. Is Charing Cross Hospital any the worse for being in Hammersmith today? Do Sloane Rangers change their accents because they have occupied Shepherd's Bush as well as Fulham?

Short-term thinking and suspect nostalgia are no basis for decisions about where best to house an opera company. ENO will most likely prosper by leaving St Martin's Lane, while the Coliseum will be all the better for returning to its roots. Tony Blair, meanwhile, will sweep the mean streets of Kings Cross clean and our only likely loss will be future performances of The Beggar's Opera: Tony will soon put a stop to that sort of sentimental nonsensen