The architect of Vote Leave tonight branded Brexit Secretary David Davis as 'thick as mince' as a row over delivering the referendum deepened.
Dominic Cummings blasted Mr Davis was also 'lazy as a toad' and 'vain as Narcissus' - the latter a mythological Greek God who fell in love with his own reflection.
The brutal jibes came amid a growing battle inside the Cabinet about exactly how the Government should be delivering Brexit.
Dominic Cummings (pictured at a Commons committee last year) tonight branded Brexit Secretary David Davis as 'thick as mince' as a row over delivering the referendum deepened
Mr Cummings, an ex-advisor to Michael Gove who spearheaded the Vote Leave campaign, has repeatedly warned Government risks squandering Brexit
Mr Davis and his team were back in Brussels today for the latest round of talks with chief EU negotiator Michel Barnier.
But the Brexit Secretary faced mockery for being photographed at the meeting with no papers while his EU rivals held thick bundles of documents.
Mr Cummings, an ex-advisor to Michael Gove who spearheaded the Vote Leave campaign, has repeatedly warned Government risks squandering Brexit.
Mr Cummings, who tweets as @odysseanproject, said today that Civil Service chief Jeremy Heywood was in a 'parallel universe' on Brexit and warned Whitehall had 'mega failed to prepare' for the negotiations.
And he jibed: 'DD (David Davis) is manufactured exactly to specification as the perfect stooge for Heywood: thick as mince, lazy as a toad, and vain as Narcissus.'
David Davis (pictured right today) faced mockery for being photographed at the meeting with no papers while his EU rivals held thick bundles of documents
Mr Cummings latest intervention came against a backdrop of bitter feuding among UK ministers over the Brexit strategy.
The first phase of the Brexit talks will cover the divorce settlement - with the main topics reciprocal rights for UK and EU citizens, the potential bill for Britain, and the Northern Ireland border.
David Davis is facing strong opposition from the EU over Britain's proposals for rights of European nationals living in the UK, as well as pressure to accept paying a huge 'divorce' bill.
Theresa May last month published a 'fair and serious' offer to guarantee the future rights of the 3.2 million EU citizens living in the UK and the 1.2 million British ex-pats in the EU.
The proposal to grant EU nationals 'settled status', effectively indefinite leave to remain, was immediately dismissed by European Council President Donald Tusk as 'below our expectations'.
Under the terms agreed between the EU and UK, negotiations are taking place in four-week 'rounds'.
The second session is beginning in Brussels today.
The EU says that only when 'sufficient progress' has been made on citizen's rights, the divorce bill and Northern Ireland will they move on to discuss future trade talks.
Both sides have committed to 'transparency', and are expected to released updates about each round accompanied by press conferences.
Over the weekend, Chancellor Philip Hammond angrily accused Cabinet rivals of trying to undermine his agenda for a 'softer' business-friendly Brexit prioritising jobs and the economy.
One unnamed Cabinet minister was reported have hit back, claiming Mr Hammond was part of an attempt by 'the Establishment' to prevent Britain ever leaving the EU.
The Daily Telegraph quoted