Sir Crispin Tickell is a former diplomat and UK Ambassador to the United Nations.

There are some curiosities in current Conservative policy on energy.

First, we have seen the dark hand of the Treasury reducing expenditure on low carbon sources without apparent regard to the implications for climate change. At the same time we have seen the Chancellor cooking up expensive new energy policies in China without apparent reference to the Department of Energy and Climate Change. We have the creation of a new National Infrastructure Commission to put together a rational and comprehensive policy to meet requirements over the next thirty years. A key aspect is the appointment of Lord Adonis to run the new Commission, and to report back before next year’s Budget.

It is clearly commonsense to join up energy and climate policy, given that it is largely through energy policies that climate targets are achieved. This was of course the rationale behind Labour’s creation of DECC in 2008. Mysteriously for a party overtly committed to acting on climate change, we saw a de facto schism open between energy and climate policy in the first months of the present government. At the level of international climate rhetoric, Britain remains a leader; at the level of national energy policy, it has rowed back on measures that reduce carbon emissions.

Do not think that such inconsistencies go unremarked in the international arena. Since the abortive Copenhagen climate summit of 2009, Britain has worked with developing countries to re-build trust and re-invigorate the international process whose health is a necessary requisite for a global climate change solution. The lead-up to the Paris summit that may see a global climate agreement signed is the worst time to be eliminating sensible measures that cut energy waste and stimulate the building of low-carbon energy systems.

The Prime Minister has commendably maintained his commitment to spending on overseas aid in the face of criticism from within and without his party, and has garnered the respect of the developing world for it, including countries with which trade is crucial to our future economic development. That respect will be much diminished if the Prime Minister allows his Chancellor to undermine our own progress on reducing emissions.

The rationale behind the Government’s recent policy reversals is hard to grasp. We are told that levies on bills that support renewable energy are unaffordable, at a time when energy bills are lower than ever. We are told that renewables must come off subsidy now, even as the Government prepares to subsidise nuclear power until 2058. We are told that the Government is seeking to deploy the cheapest low-carbon generation, and then watch it destroy the industries that give us the cheapest low-carbon generation – onshore wind and solar. It is perplexing; but the long-mooted “re-set” of energy policy that we now anticipate offers an opportunity, if I may adopt a phrase coined in rather different circumstances, to go back to basics.

First, an energy policy set solely according to today’s immediate concerns (whether “keeping the lights on”, as it is this week, or affordability, as it was a few months ago) is no policy at all. Energy infrastructure endures for decades, and the investment cycle is similarly long. Over decades, we need to ensure security of supply, decarbonise, and do both of these as affordably as possible. That necessitates a long-term vision, proper planning and policy consistency, which in turn keep costs low by giving confidence to investors.

Secondly, the cheapest form of energy is to use less. Thus the Government needs ambitious and evidence-based policies that cut energy waste and make each watt that we use more productive. Doing so will reduce bills, reduce reliance on imports from overseas and reduce carbon emissions.

Thirdly, Britain is not the only nation wrestling to accommodate the energy “trilemma”. If we can learn from others’ experiences, we should. The US, for example, shows us the value of demand-side measures for affordability and the security of electrical grids. Germany shows us the value of having a long-term plan and sticking to it. Denmark shows us that high levels of intermittently generating renewables can be accommodated in the electricity system if other necessary measures are implemented too. The world is full of good examples if ministers will but look for them.

Fourthly, we live in an integrated world. If China, the US and our main European allies are decarbonising their economies, as they are, it is nonsense to assume that our self-interest lies in the opposite direction. One wonders how Presidents Xi and Modi, both of whom have established extraordinarily ambitious programmes for renewable energy, viewed the solar wasteland that they saw in Britain during their recent visits.

This much should be the first item in the in-tray of every DECC minister and every government energy advisor. One trusts that they are very much in the mind of the formidable Lord Adonis as he contemplates the landscape before him, before beginning the report promised for next year.

A political generation ago, the Conservative Party – through Margaret Thatcher – gave global leadership on climate change. Now, what leadership there is seems to come from China and the United States. As the world’s two biggest greenhouse gas emitters, this is very welcome. But it does not mean that Britain’s logic lies in reversing direction. There is neither need nor rationale for rolling back our low-carbon policies. This government should remain true to the vision given by Lady Thatcher many years ago.