Dominic Cummings has blasted Boris Johnson and his office for falling "so far below the standards of competence and integrity the country deserves".
In a lengthy statement, the PM's ex-aide denied being the source of leaked messages from Mr Johnson's phone and tore into his former boss.
And in an explosive claim, he suggested Mr Johnson was prepared to potentially break electoral law by asking donors to pay for the refurbishment of his Downing Street flat.
Mr Cummings was blamed by No10 sources after texts between the Prime Minister and businessman James Dyson ended up in the hands of the BBC.
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