It took just 15 minutes for 25 volunteers to transform the bare square of grass struggling against oncoming winter into a shining, spinning field of multicoloured pinwheels.

Passers-by stopped to admire the whirling colours, posing for photos with bunches of pinwheels - held as if flowers - and grinning at the sparkle brought to an otherwise dour and empty plot.

The location? Parliament Square, Westminster. The day? Yesterday, 17th November - the day the UK government formally ratified the Paris agreement.

The reason? To celebrate the 18,000 signatures climate charity 10:10 gathered to demand the UK government does not give more public money to dirty fossil fuel power stations than to clean onshore wind power.

But the pinwheels we placed down also represent the UK's lost onshore wind turbines - a generation of clean energy trendsetters locked out of the energy market by the government's nonsensical and contradictory ban on onshore wind power.

Yes, I said ban. A ban on the cheapest new form of power generation, on a technology that already provides 6% of the UK's electricity (and climbing) and on a clean energy choice that has the backing of 73% of the UK public. And don't forget: we're the windiest country in Europe.

How did it come to this?

In the run up to the 2015 general election the Conservative party inserted a clause into its manifesto pledging to "halt the spread of subsidised onshore wind farms".

Broadly seen as a concession to English Tory backbench MPs - either ideologically opposed to wind power, or of the (contestable) opinion their constituents are - it was likely to have been traded away in the expected post-election coalition negotiations. Except there were no coalition negotiations.

Instead a surprise Tory government, blinking in the daylight of power untrammeled by pesky Liberal Democrats, found itself with two contradictory manifesto pledges:

First, the promise to end subsidies to onshore wind;

Second, a commitment to achieve the "lowest cost decarbonisation" for the taxpayer.

The problem: onshore wind is the cheapest form of new power capacity we can build, on par with new gas fired power stations. By several estimates it can already undercut them in prime locations.

That trend will only continue: even the government has admitted as much. The new Business, Energy & Industrial Strategy department's updated report on cost projections for different technologies shows onshore wind becoming indisputably cheaper than new gas by somewhere between 2018 and 2020. By 2025 they expect it to leave gas for dead on cost. Game over.

The age where homegrown clean energy beats old-school fossil generation is not some distant dream, It's poking its head around the corner. Or even standing right in front of you.

The fact is you can't design a 'lowest cost' transition to a low carbon economy while leaving out onshore wind power. So instead the government is paying lip service to a 'lowest cost transition', playing it safe with its backbenchers, and kicking onshore wind power out into the cold.

Project 'kill off new wind power'

It used two routes to achieve this. First, it closed the Renewables Obligation scheme early for onshore wind and made clear that the technology would not be allowed to bid into the scheme's successor, 'Contracts for Difference' auctions.

After a grace period of nine months, starting in May 2016, there will be no public financial support available to onshore wind power. Due to EU state aid rules this decision also means (for as long as we remain in the EU) that there can be no support for commercial scale solar either - meaning the two cheapest low carbon energy sources are off the table.

Next, the government erected two new planning hurdles, both decreed through a written ministerial statement requiring no parliamentary scrutiny.

First, onshore wind applications can only be successful if they relate to sites pre-allocated for onshore wind development in local plans produced by local authorities. Though this sounds reasonable it effectively kills the onshore wind pipeline in its tracks: local plans have five year cycles and most authorities don't have the resources to accurately identify appropriate sites. It also gives anti-wind local authorities an effective political veto over any proposals before they've even started.

Second, onshore wind applications must be shown to have the 'full backing' of local communities - an impossibly vague criterion not extended to any other type of planning application. Is a single objection enough to kill a project? No one knows. The risk threshold for new applications just got too high for anyone to hurdle.

Double standards

Now look to fossil fuels.

First, through the subsidy lens. Since 2014 £1.8bn has been allocated to fossil fuel power stations through Capacity Market auctions, designed (not very well) to ensure future security of electricity supply. £550m of this has gone to coal and diesel generators, the James Bond baddies of the power sector. Another £1bn will go to already existing fossil power stations in auctions to be held in December and January.

Why all this money to fossil? Simple: all generation technologies - new, old, dirty, clean - need public support to bring investment in new capacity forward. The myth that only renewables need subsidy is just that - a myth.

Yet it seems we've got billions to pay polluters simply not to close - but no more in the bank to support cheap, popular and clean onshore wind power.

Second, to planning - and the buccaneering fracking strategy we're told will lower bills (something the Advertising Standards Authority had to correct the government on) and create energy security. The government is proudly going all out for this increasingly unpopular choice, dreaming up (widely mocked) financial wheezes to win over local residents, and swatting away local council decisions to block fracking wells in Lancashire.

In the case of wind, 'giving communities the final say' means they can decide as they wish, so long as they say 'No'. When it comes to fracking it's the reverse: local communities can have all the say they want, but unless it's a 'Yes', their decisions will be overruled by Westminster.

It's not the only measure on which onshore wind farms and fracking inhabit opposite ends of the spectrum. While recent government polling found public support for onshore wind at its highest for years, at 71% (echoing 10:10's own polling showing , where support remains high at 65% even in rural areas), support for fracking keeps tumbling, reaching a new nadir of 17% just 3 weeks ago.

Flying in the face of public opinion, expert advice and common sense

In fact the government's energy policy in direct opposition to public opinion. Wind is popular, it's cheap, it works - but it's banned.

When a BBC journalist recently pressed UK energy minister Baroness Neville-Rolfe on how she proposed to deliver low carbon power at minimum cost to consumers while excluding wind, the cheapest form of green generation, she was reduced to mumbling incoherently until whisked away by aides.

That is why 10:10 volunteers carpeted Parliament Square in pinwheels yesterday - to begin the fightback against a supremely political decision that threatens to set back the UK's climate action plan and undermine this low carbon industrial success story. Our target: Philip Hammond, Chancellor of the Exchequer, who is to deliver his Autumn Statement next week, on 23rd November.

Our petition demanding that his statement includes public support to allow onshore wind power to fairly - and successfully - compete against other electricity generators is just the start. In 2017 we'll turn our sights to planning, and begin the work to put the wind back in the sails of the UK's low carbon transition.

It's simple: we can't let onshore wind be hung out to dry!

Action: sign up at 1010uk.org/blownaway to add your voice and be the first to hear about campaign developments. See also petition text.

Max Wakefield is the lead campaigner at climate change charity 10:10. Before joining he worked with grassroots groups on issues of energy and finance.