Like two fractious little boys trading playground insults they know are escalating out of control, the pair had been sparring all day – until one of them finally blurted out the slur he knew might end their friendship for ever.

'Time to drop the really big bomb,' wrote Elon Musk on his social media platform X on Thursday afternoon.

'Donald Trump is in the Epstein files. That is the real reason they have not been made public. Have a nice day, DJT!'

Musk didn't offer any clarifying evidence but soon added: 'Mark this post for the future. The truth will come out.'

The extraordinary implosion of the friendship and alliance between the world's richest man and the world's most powerful man has proved mesmerising.