The Duke of York is preparing to give formal evidence to a US criminal investigation into the disgraced paedophile Jeffrey Epstein, The Telegraph can disclose.

In an unprecedented move, the Duke announced on Wednesday evening that he was stepping back from public life in the wake of a BBC interview over his friendship with Epstein that backfired in spectacular fashion.

A well-placed royal source said on Wednesday night that the Queen had summoned the Duke to Buckingham Palace to effectively sack her second-born son – said to be her favourite child – from official duties, ordering him to stand aside. The Prince of Wales, who is on a tour of New Zealand, was consulted by telephone.

City sponsors deserted the Duke’s flagship projects while major charities were planning to ditch him as their patron. A planned visit to flood victims in South Yorkshire were abandoned in the aftermath of his “excruciating” Newsnight performance.

Buckingham Palace is understood to be braced for US authorities to issue the Duke with a subpoena, requesting he gives testimony under oath over his friendship with Epstein. Sources have suggested the summons is “imminent”.