Prince William is reportedly giving “serious” thought to giving a younger member of the Royal Family a new title when he becomes king.

Lady Louise Windsor, 21, the daughter of Prince Edward and Sophie Wessex is becoming increasingly popular with fans of the Royal Family.

She has recently joined the St Andrew’s University Officers Training Corp while away studying. It is a similar move to a young Queen Elizabeth II who joined the Auxiliary Territorial Service (ATS) in 1945.

It has led to mounting speculation that the Prince of Wales, 42, could give Louise a new title when he takes the throne.

One source told New Zealand Woman’s Day: “William’s serious about making her a working royal. He’s even prepared to give her a new title.

“The devotion she has shown over the years will only improve after military service – she’s a very impressive young lady.”

Edward and Sophie made the decision not to give Louise, and her brother Viscount James, the Earl of Wessex, HRH titles when they were born. The couple hoped it would allow the pair to live a normal life away from the spotlight.

And when she turned 18, Louise could have started using the Princess title, reports the Scottish Daily Express, but opted not to. James is expected to make a similar decision when he turns 18 in December.

Although reports suggest William is keen to have Louise as a major part in The Firm, her mother says she and James are both “unlikely” to ever take the titles of Prince and Princess.

Both James and Louise have kept relatively low profiles so far, mostly attending engagements with their parents. Louise however was a bridesmaid at William and Princess Kate’s wedding.

Meanwhile, Daily Beast royal editor Tom Skyes says William’s plans for the monarchy could look very different to the current Firm, with Princess Anne, 74, said to be among those who would not be involved. He says Anne’s “raison d’être is zooming around the country squeezing in 500-plus engagements a year”.

He added: “William has made it very clear he doesn’t see that as the family’s role anymore, preferring a tiny number of limited, high-impact engagements and events to the paternalistic, seen-to-be-believed, helicopter-riding royal attitude of old.”

Kensington Palace has been approached for a comment.