Does the Queen ever wake up at Buckingham Palace, I wonder, and think "hmmmm, what one really needs is more space, let's get young Linley round and put a big spiral thingy on the south lawn"?

I blame all those toshing-up-homes television programmes of the pre-credit crunch years. While the gardening shows explained how to trash the garden - a fashion faithfully followed by many museums - the myriad home improvement versions demonstrated how to wreck any building in three easy extensions.

All around me in suburbia, the results are apparent: a shoebox loft conversion plonked on every roof, a plastic and glass conservatory box shoved into every garden.

The Polish builders have now packed up their white vans and shot off home, but it's rare to cross a museum threshold without bumping into the architect's model of the proposed extension, that desperately needed archive/education space/conservation centre/temporary exhibition space (and inevitably, bigger shop and cafe, and corporate entertainment space just in case the corporates ever come out to play again).

You have to have some sympathy for the all-mouth-and-no-trousers buildings, such as the National Maritime Museum in Greenwich or Tate St Ives, whose swaggering facades conceal remarkably meagre galleries, but do all the remorseless improvers really need that extra space?

When the Victoria and Albert Museum (V&A) was desperate to build the Spiral, it appeared the museum would grind to a halt if they didn't get it, just as the British Museum and Tate Modern are now explaining.

But the V&A didn't get it, and life went on: somehow, it turned out, there was room for a string of new galleries, and even to take in the poor benighted Theatre Museum, whose own architect's model is probably still somewhere in the collection.

In suburbia, as the lights come on in the dusk, most of those conservatories and garrets remain dark: actually, it turned out, there was room enough for everyone in the kitchen - and that's where everyone stayed.