The Queen's youngest grandchildren, Lady Louise Windsor and James, Viscount Severn, are the only male-line grandchildren not to hold Prince or Princess titles - but that could change.
Lady Louise Windsor, who turned 18 last year, wasn't well known during her childhood, however has made a number of public appearances following the death of Prince Philip.
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Louise is the daughter of the Queen and Philip's youngest son, Prince Edward, and his wife Sophie the Countess of Wessex.
The reason behind Louise and her brother James not carrying the title dates back to her parents' wedding day in 1999, when they were bestowed with the titles the Earl and Countess of Wessex, much to the surprise of royal fans.
The decision broke centuries of tradition, however Buckingham Palace explained the plan was for Edward to be created Duke of Edinburgh upon both the death of his father and accession of elder brother.
After Lady Louise's birthday in November, she had the right to make her own decision about whether she wanted a title and could opt to become Princess if she wishes - but her mum says that's unlikely.
In 2020, the Countess of Wessex told The Sunday Times: "We try to educate them with the understanding that they will most likely have to work for a living. That is why we made the decision not to use HRH titles. They have them and can decide to use them after 18, but I think it is very unlikely."
During an earlier interview for the Queen’s 90th birthday in 2016, Sophie joked about Louise's realisation that her grandmother was the Queen.
"I mean Louise had no concept really that the Queen and her grandmother were one and the same person," she told Sky News.
"It wasn’t until she was at school that other children were mentioning it and saying, 'Your gran is the Queen'. And she'd come home and say, 'Mummy, they say that Grandmama is the Queen.' And I said, 'Yes,' and she said, 'I don’t understand what they mean.'"
