The Coalition Agreement was unambiguous on the question of public subsidy for new nuclear power stations: there would be none. It stated:

Liberal Democrats have long opposed any new nuclear construction. Conservatives, by contrast, are committed to allowing the replacement of existing nuclear power stations provided that they are subject to the normal planning process for major projects (under a new National Planning Statement), and also provided that they receive no public subsidy.

But this pledge is flatly contradicted by today's deal on a new plant in Hinkley, which guarantees the French-owned EDF and Chinese state investors a strike price of £92.50 per MegaWatt Hour, nearly twice the current market rate for wholesale energy, over a 35-year period.

When I put this point to the Prime Minister's spokesman at this morning's Lobby briefing, he replied:

Today is a very important announcement, it's around, as he [David Cameron] described it, long-term planning for our economy, for energy security, actually for jobs as well, there are 25,000 jobs associated with today's announcement, and we need this broad energy market and that's why today's announcement is a very important one.

I replied that this was an explantion of why the investment was needed, not of why the position had changed, and he said:

I actually think that the position around the need for energy security, the need for more competition in the market, that has been the government's policy and you're seeing a very important announcement today in regard to that.

So No. 10 is refusing that deny that the coalition has broken its 2010 pledge on public subsidy, simply because it cannot credibly do so. Should wholesale prices fall or rise at a slower rate than expected, it is the public who will pick up the tab in the form of higher bills (which are expected to rise by around £8 as a result of today's agreement) or higher taxes.

But if it is remarkable that the Tories, who dismiss a two-year energy price freeze as "socialism", are willing to guarantee foreign state-owned companies prices for 35 years, it is even more remarkable that the Lib Dems have gone from opposing any new nuclear power stations to supporting a multibillion subsidy for them.