Last Saturday - two days after Madeleine McCann went missing on the Algarve - I saw two photographers and counted just four satellite-broadcast vans.  Today, along a minor access road beside the apartment block where Madeleine McCann was stolen while sleeping, I can see a total of eleven satellite vans and at least twenty photographers.  Sir Trevor McDonald's been in town broadcasting from a holiday-apartment balcony, the BBC and Sky are live on the hour, every hour. Often for hours. Glance up at the sky and chances are youll see a helicopter or a pleasure plane overhead. Odds-on, it's a British media charter-flight. 

One tiny corner of Portugal is under media siege. 

What's changed since Saturday, when this was a big story but not yet the massive drama it's become?   And why have the people of Praia da Luz begun to turn against us? 

It's the media economy, Stupid. 

Like every market, news is about supply and demand. In this case, supply is the story and the elements of it; demand is the appetite for that story  people's willingness or desire to spend time and money consuming it. Last Friday, when news of Madeleine McCann's abduction broke, supply peaked and found a satisfactorily high level of consumer demand. 

The market was a happy equilibrium, with the value of a journalist on the ground, high.  I, a lowly reporter on More4 News, had just arrived into Portugal on holiday but by Saturday was reporting live for Channel 4. Since the weekend, though, the equilibrium's been broken.  Demand - from consumers as channelled through journalists - has, if anything, grown.  Supply has all but dried up.  Therein lies the problem.

Take the supply side first.  After a British crime, the first place to look for more of the raw material is the police: a mine, if you like, of information about their ongoing enquires.  In Portugal, the law of 'the secrecy of justice' means that particular mine has been closed down.  In the absence of 'official' news, reporters start to look elsewhere: a hundred or so journalists chasing down the thousand or so permanent residents of Praia da Luz.  After a few days of the same questions, people start to get a little frustrated. 

One woman, her face on fire, told me yesterday how a television journalist had 'bribed' a young mother to let him interview her kids. As he finished he turned around to the mother, with a broad grin on his face and two thumbs up - "that'll have 'em weeping in the aisles". "Disgusting", my interviewee said, "He doesn't care about Madeleine, he just wants his scoop." In the absence of proper news, interviews like that become the surrogate sources of supply.  She went on, "My husband - and he's a pretty mild man - saw that Trevor MacDonald on a balcony overlooking the McCann apartment. 'Bugger off, Sir Trev!' he shouted".  Funny things happen when markets get out of sync.