The so-called brains behind Brexit who called Brexit Secretary David Davis “thick as mince” has taken a new stab at the Government for its alleged failings in leaving the EU.

Dominic Cummings told Prospect that Theresa May and Mr Davis "have provided a case study of grotesque uselessness" in the way they are dealing with the Brexit process.

The mastermind behind Vote Leave added that negotiations were in a "dire state" and the UK is close to messing up the talks completely.

Mr Cummings, who recently deleted his Twitter account, also said it was "crazy" of Ms May to trigger Article 50 in March without preparing - before or after.

"If there’s no deal, there will be significant problems that were completely avoidable," he told the publication.

Mr Cummings, the former special advisor to Michael Gove, predicted there would be an "inevitable inquiry" into why Brexit occurred, and said that "schoolchildren will shake their heads in disbelief that such characters could have had leading roles in government".

Brexit: the deciders Show all 8 1 /8 Brexit: the deciders Brexit: the deciders European Union's chief Brexit negotiator, Michel Barnier Getty Brexit: the deciders French President Emmanuel Macron Getty Brexit: the deciders German Chancellor Angela Merkel Reuters Brexit: the deciders Commission President Jean-Claude Juncker EPA Brexit: the deciders The European Parliament's chief Brexit negotiator Guy Verhofstadt Getty Brexit: the deciders Britain's Prime Minister Theresa May Getty Images Brexit: the deciders Britain's Chancellor of the Exchequer, Philip Hammond PA Brexit: the deciders After the first and second appointed Brexit secretaries resigned (David Davis and Dominic Raab respectively), Stephen Barclay is currently heading up the position PA

In the six months after triggering Article 50, negotiations have stalled, despite Ms May’s key Florence speech to get talks moving again.

Senior ministers have also said the "no deal" scenario is still possible, carrying on Ms May’s rhetoric of "no deal is better than a bad deal".

Mr Cumming’s gloomy outlook also comes shortly after US President Donald Trump slapped 300 per cent tariffs on Irish-Canadian Bombardier planes, attempting to eliminate competition for US-based Boeing. The controversy has, according to some analysts, given the UK a hint of the nature of post-Brexit trade deals.

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The former Vote Leave chief has never minced his words, however. He also called Mr Davis "lazy as a toad" and declared that the Government decision to leave the European Atomic Energy Community was made by "morons" who were "near-retarded on every dimension".

Prospect readers did not all appear convinced that Mr Cummings was right to criticise.

"This display of rare political courage should not go unrewarded; surely the PM must find him a seat in the Cabinet where he can lead the other failures and enjoy the fruits of the inevitable outcome […] He deserves no less!" quipped one reader.

He was also accused of hypocrisy by Prospect readers when he accused Government of having no plans for the future.

In an essay for the Spectator, Mr Cummings – a man David Cameron once described as a "career psychopath" – said Brexiteers won the referendum by talking about immigration and the promise of £350 million per week for the NHS.