The Duke and Duchess of Sussex believe that the Queen failed to take “full ownership” of the race allegations made in their Oprah Winfrey interview, according to the authors of unauthorised biography Finding Freedom.

       A friend of the couple told Omid Scobie and Carolyn Durand that Her Majesty’s lack of action had prevented them from moving forward.

       The source also suggested that the Queen’s assertion that “recollections may vary” about their claims had not gone down well.

       The Queen has until now been one of the only senior members of the Royal family to escape the ire of the Sussexes, who have gone out of their way to single her out for praise.

       However, a new epilogue to Finding Freedom, excerpted in People magazine, suggested that the Duke and Duchess feel frustrated that she did not follow through with her promise to address their concerns.

       It said: “The Queen’s ‘recollections may vary’ comment ‘did not go unnoticed’ by the couple, who a close source said were ‘not surprised’ that full ownership was not taken. ‘Months later and little accountability has been taken’, a pal of Meghan added. ‘How can you move forward with that?’”

       The Sussexes made a series of allegations about the Royal family during their two-hour televised interview with Winfrey in March.

       The most damaging came as the Duchess, 40, alleged that when she was pregnant with their son, Archie, “concerns” had been raised by a member of the family about the colour of his skin.

       She also suggested that when she had felt suicidal, the institution had failed to help her.

       However, the Duke insisted: “I would never blindside my grandmother, I have too much respect for her.”

       The Queen reacted to the interview by insisting that the couple’s allegations would be “taken very seriously”.

       “The issues raised, particularly that of race, are concerning,” she said. “Whilst some recollections may vary, they are taken very seriously and will be addressed by the family privately.”

       Finding Freedom, published last summer, will be republished in paperback on August 31 with a new epilogue summarising the dramatic events of the past two years.

       In an interview to promote the new edition, Mr Scobie claimed that one of the lessons the Sussexes had learnt was to prioritise their mental health and keep “some of the toxicity” at an arm’s – and ocean’s – length.

       ‘A new era of visibility’

       He also told People magazine that as their period of shared parental leave drew to a close two months after the birth of daughter Lilibet, the couple were entering a new “era of visibility”.

       He said: “They’re a couple who do very well in those moments of human interaction. They need to be on the ground. They say that the proof is in the pudding, and what we are about to see is that pudding.”

       Mr Scobie’s comments raise the prospect that the Sussexes will take part in royal-style walkabouts on US soil.

       The epilogue is expected to cover the Sussexes’ interview with Winfrey, the bullying allegations made against the Duchess by royal staff, which she denies, and the Duke of Edinburgh’s death.

       It is also likely to touch upon the couple’s multi-million pound deals with Netflix and Spotify, as well as the Queen’s decision to strip them of all royal patronages earlier this year.

       The Duchess has insisted that they did not collaborate with the authors. However, she admitted in court documents related to her privacy action against The Mail on Sunday that she did not know if the Kensington Palace communications team had provided information on her behalf and that on one occasion, she did pass information to them via an intermediary.

       A witness statement lodged with the court on her behalf suggested the book was full of mistakes.

       Buckingham Palace declined to comment.