It is a fact not generally appreciated that one of the first successful windfall taxes on a hated group of businesses seen as profiteering from exorbitant charges to consumers was imposed by the woman now known as Baroness Thatcher, who handbagged the banks in the early 1980s.

In 1997 new Labour hit all the privatised utilities for £5 billion. Bliss it was to be alive; it was to pay for Welfare to Work, the bill was spread wide, and the utilities scented the public mood in those heady days and paid up. The landscape is different now, and the threat of a smash-and-grab raid on our vilified energy firms is rousing some spirited opposition.

The Treasury probably understands the arguments against as well as anyone. Yet there is a danger, as union leaders and consumer groups vie to step up the pressure for a one-off hit stretching into the billions, that an administration seemingly heading into the history books will give in to the temptation for one last, rabble-rousing gesture.

No one enjoys paying fifty-quid-plus to fill up the modest family saloon; no one wants to pay a grand a year to heat the modest family home. The sight of those businesses responsible suffering some proportionate pain would give pleasure to millions. However, although windfall taxes — like bear-baiting — may offer a spectacle, it is not an improving one.

Any energy windfall tax would not be hypothecated to cut the fuel bill of that pensioner with the stone cold one-bar fire; it would go into the morass of central public spending, to be frittered away accordingly on whatever measures seemed most effective to reduce the cull of marginal seats.

Secondly, energy markets are increasingly globalised. That hardly needs stating in the case of Shell; but it is worth pointing out that Centrica, aka “British” Gas, recently decided, on grounds of the respective returns available, against investment in a Thames wind farm in favour of one onshore in the US.

With firms such as E.ON and EDF, which seemingly last night was in two minds over whether or not to buy our nuclear industry, heavily embedded in the UK, investment decisions are being taken in Paris and Düsseldorf, not London. These need the reassurance of a stable tax regime. Much of our energy infrastructure dates from the 1950s or before. One of the factors behind soaring gas prices is earlier under-spending in gas storage. National Grid needs huge investment. All those wind turbines in the north of Scotland need linking to the Grid.

Someone has to help to build the next generation of nuclear power stations. Who plans to take a quarter of British Energy if it is eventually bought by EDF, with the intention of doing just that? Centrica, oddly enough.

The third point, also blindingly obvious, one might have thought, is that those headline “obscene” profits already attract tax. Centrica pays 75 per cent on its Morecambe gasfield; some Shell North Sea fields attract the same rate. Sam Laidlaw, Centrica’s chief executive, claims his company, paying 58 per cent across the group, is already the most heavily taxed in the FTSE 100.

Energy prices are rising for reasons entirely unconnected to boardroom rapacity, such as scarcity, the cost of protecting the environment and the desire of billions in the developing world to own a fridge, please. And heat their homes. Use of a car would be nice.

Centrica, Shell and their confrères are never going to top those lists of our most admired companies. Yet I do not believe that the Government would be silly enough to slap a tax on energy firms. For anyone tempted by such an abrupt and destabilising change to the tax regime, just two thoughts: CGT and the 10p tax-band disaster.

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