Environmental activists have withdrawn an advertising campaign after being accused of making false claims about the price of wind energy.

The poster, launched in September by Doctor Who star Peter Capaldi and plastered around Westminster Tube station and across London’s transport network, claimed the price had fallen by 50 per cent over the past two years.

But, following a complaint to the Advertising Standards Authority, Greenpeace and a coalition of other environmental groups and green energy suppliers agreed not to use them again.

The poster, launched in September by Doctor Who star Peter Capaldi and plastered around Westminster Tube station and across London’s transport network, claimed the price had fallen by 50 per cent over the past two years

The complaint was made by the Global Warming Policy Foundation, which said the ‘50 per cent off’ claim was ‘false and misleading’ because the price paid for electricity from offshore wind farms has not halved at all in recent years.

It said the campaign relied on prices quoted for the cost of wind energy in 2022 – £57.50 per megawatt hour, down from £117.14 in 2015.

Many of the wind farms supposed to produce this energy have not even been built yet and there is no guarantee they will go ahead.

The complaint was made by the Global Warming Policy Foundation, which said the ‘50 per cent off’ claim was ‘false and misleading’ because the price paid for electricity from offshore wind farms has not halved at all in recent years

It is understood that Greenpeace led the campaign, which was supported by other organisations including ScottishPower, SSE and World Wildlife Fund.

GWFP director Dr Benny Peiser said: ‘The claims in the Westminster offshore wind campaign are some of the most blatant distortions of the truth that I have seen in pro-wind advertising.’

He said the groups had targeted Westminster station in a bid to influence ‘MPs, peers and other decision makers’.

The ASA said it considered the case closed after Greenpeace gave an assurance that it would not use the disputed claims in any future campaign.

Hugh McNeal, Chief Executive of RenewableUK, the trade association representing the wind industry has since contacted us to say the prices quoted in the campaign were bids for three offshore wind projects, which were announced by the Government in September after winning “fiercely competitive” auctions to start generating power in the early 2020s.

He said: “The bids came in as low as £57.50 per megawatt hour – cheaper than new nuclear and gas-fired power stations. This is a record-breaking 50% drop in costs; in the previous auction in 2015, the average cost of projects starting to generate before the end of this decade was £117.14 per megawatt hour.”