As the summer selling and buying holiday starts to stretch from Easter to September, just where can the buyers be hiding out, asks Angela Pertusini.

Global warming has had its impact on London's property market just as markedly as it has on the polar ice caps and the increasingly Armageddon-like hurricane season: our summers are getting longer and, in property terms, that is a disaster.

Always deemed the slackest time of the year to sell your house, summer is encroaching ever-further on the year so that it is now snapping at the heels of the Easter weekend - which only a decade ago was considered the busiest time in any self-respecting estate agent's calendar - and stretching well into September.

When you factor in that the selling of houses is almost as bad in the Christmas period - and that now means late-October to mid-January - the opportunity to shift anything other than seaside cottages and timeshares in Lapland is becoming extremely tight.

Basically, if you don't bag a buyer during City Bonus season - January to the end of March - you're playing roulette with how long your house will be on the market and what it will fetch when it sells. Forget the fact that your garden will be looking its best during late spring, that the rooms will be filled with natural light and the condensation-streaked windows and Siberian bathroom will be just a distant memory, no one, we are told, wants to buy in summer.

I can understand why buying a family house in the summer may not be that appealing - it may involve moving schools and really, you want to be in and settled by September, not starting the whole beleaguered conveyancing process in the middle of the holidays - but flats? Pied-a-terres? Delightful Victorian artisan cottages? Surely really committed buyers don't migrate to the Costas for months at a time?

The good news for those buyers who aren't bothered about acquiring a really deep tan, by the time August rolls around, many unfortunate sellers have reached that level of despondency where offers will be entertained.

It used to be just the rank old properties left by this stage but, as the summers get longer, it just takes a badly timed divorce or probate award to mean that there are some genuinely nice homes with some genuinely anxious vendors out there.

Of course, this is true of only a certain, earthly level of property. Up there in the property stratosphere, normal rules have not applied for some time and since buyers are as likely to be anywhere in the world when they are trying to buy a home in London, there is no such thing as a closed season. So thankfully the sellers of London's most expensive one-bedroom flat which went on the market this month have nothing to worry about.

It is a matter of record that, whenever any truly ludicrous sum is asked for a property, be it converted broom cupboard, beach hut or even air space, estate agents will fall over themselves to justify the level of sheer venality behind it.

So, no, £3 million for a one-bedder is not obscene, we are told. Location is everything and this one is in Eaton Place at the heart of Belgravia. "We should not think of £3 million for a one-bedroom flat as being overpriced or extortionate," said one. Another described it as "a sound investment" and a third went on record as saying "if London wants the benefits and opportunities that stem from being a global city, we will have to get used to these prices".

It's easy to bluster and froth at such prices and such snooty defences but this launch occurred in the same week that news was leaked that Irina Abramovich was outbid on a house around the corner from Eaton Place.

Irina is Britain's wealthiest divorcee, having just relieved oligarch and Chelsea FC owner Roman of upwards of £150 million. Apparently the £35 million she offered simply wasn't considered enough. Nor will it be in the future. As more and more global billionaires pile into the capital, the likes of Irina, merely super-wealthy, are going to feel the squeeze.

A couple of months ago I reported Candy & Candy's plans to build the world's most expensive apartments at One Hyde Park - the penthouses, it was rumoured, would be priced at £84 million or £4,000 per sq ft, more than double London's ceiling price.

Already it seems that may have been exceeded by Richard Caring who is developing the former US Navy offices in Grosvenor Square in Mayfair. Having paid £2,500 per sq ft for them, he is going to at least match One Hyde Park's rates to show any profit.

I doubt whether I'll ever get to find out what goes inside a building to command those sort of prices but I can't wait to hear how the West End's finest champion them.