Princess Beatrice, 32, and her husband Edoardo Mapelli Mozzi announced they are expecting their first child. Their royal baby is due in autumn and fans were delighted to see Beatrice's blossoming baby bump when she stepped out at Wimbledon tennis tournament last week.

       Beatrice is the eldest child of Prince Andrew, 61, and Sarah Ferguson, 61, and while her sister Princess Eugenie, 31, gave birth to a baby boy in February, her son August did not take a royal title.

       Andrew is the Queen's second son and has held onto his Duke of York title despite withdrawing from public life in November 2019.

       The law of male primogeniture means peerages can only pass down the male line of the family which means only sons, nephews or grandsons can inherit them.

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       Beatrice is 10th in line to the throne and is not a working royal.

       While she received a royal title at birth the same will not apply to her offspring as the privilege is only automatically granted to grandchildren and not great-grandchildren of the presiding sovereign.

       If Beatrice has a son then it seems logical he might inherit Andrew's Duke of York title but this is highly unlikely to be the case.

       According to a constitutional expert either sixth in line to the throne Prince Harry, 36, or Kate, Duchess of Cambridge and Prince William's youngest Prince Louis, three, are most likely to inherit the title.

       The peerage will only pass on following Andrew's death at which point it will merge with the crown and be redistributed as the presiding sovereign sees fit.

       Constitutional expert Iain MacMarthanne told Express.co.uk: "Without a son, and by the terms of the letters patent under which the dukedom of York was again created in 1986, the death of the present duke will see the title merge with the crown."

       Harry could be granted the title if his father Prince Charles, 72, is king at the time of Andrew's death.

       Mr MacMarthanne explained: "Historically it is a title that has been granted to the second son of the sovereign.

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       The expert added: "Arguably, with Charles’s accession, Prince Harry, Duke of Sussex becomes the sovereign's second son and could under the custom become the next duke of York in addition to being duke of Sussex.

       "The fashion for creating multiple dukedoms, such as during the reign of Victoria has however died out.

       "Additionally, the custom of new creations has invariably become linked with marriage and as that has already occurred, together with his withdrawal from front line royal duties, his creation as Duke of York seems unlikely, should the title be available."

       Mr MacMarthanne argued that Louis, three, is most likely to be the next Duke of York, as Prince William is most likely to be king at the time of Andrew's death.

       The expert added: "As such, Prince Louis of Cambridge is presently the most likely candidate to become the next Duke of York.

       "However, it will be for the sovereign of the day to determine its usage when it becomes available to be granted in future generations."

       Beatrice and Edoardo are regulars at Royal Family events but as non-working royals, they are expected to raise their child out of the spotlight.

       In the rare instance, they were offered a title for their baby from the Queen they would probably choose to reject as has been the case with a number of younger royal parents.