The briefing by the Prime Minister’s official spokeswoman took journalists by surprise.

Asked what the Government’s advice to motorists was with the threat or an impending strike by petrol hauliers she replied that businesses and individuals should make whatever contingency plans they deemed necessary.

Pushed on whether she was advising motorist to panic buy she didn’t retreat. Motorists “will draw their own conclusions”, she said.

At first it was suggested that the move was part of a cynical attempt by Downing Street to move the news agenda on from tales of late night supper for Tory donors in Downing Street.

But as motorists up and down the country took the Government’s advice to heart it became clear in Westminster that the move was actually part of a deliberate strategy to try and undermine the effectiveness of any strike before it happened.

Ministers were working under the assumption that, because of the financial costs to the workers involved, if and when the strikes do happen they will last no longer than four days at a time.

One said that they had calculated that there is three times more petrol storage capacity in people car tanks than there is nationally in forecourts and storage facilities.

Far better, their argument went, that motorists panic bought now when fuel supplies were running normally than in the few days running up to a strike when supplies were about to be suspended.

But quite apart from the dangers of people stockpiling gerry-cans of flammable fuel in their homes for the next few weeks the Government initiative appears to have other flaws as well.

The Retail Motor Industry Federation estimates there are now 6,000 fewer forecourts than there were at the time of the fuel blockade in 2000 making it far easier than it was for fuel shortages to become a self-fulfilling prophecy – even with supplies uninterrupted.

This could mean some petrol stations temporarily running out of fuel and making it harder for those who really do need petrol to get it.

And then there is the crying wolf problem. With unions and employers likely to sit down at the conciliation service ACAS in the next few days any strike is now likely to be weeks away – by which time most of the hoarded fuel will have run out.