Hugh Grosvenor and his new squeeze Harriet Tomlinson.

Hugh Grosvenor, 26, was thrust into the spotlight last year when his father died of a heart attack aged just 64, making him the seventh Duke of Westminster.

Hugh Grosvenor at the wedding of Lady Melissa Percy and Thomas van Straubenzee at St Michael's church in Alnwick.Source:australscope

His dad Gerald’s surprise death also meant he inherited a whopping £9.3 billion ($15 billion), and 300 acres across London’s Mayfair and Belgravia, as well as estates in Oxford, Cheshire, Scotland and a slew of other properties around the globe.

But now the young duke — reportedly the richest man in the world under 30 — is set to break hearts.

The 7th Duke of Westminster, Hugh Grosvenor, arriving for a memorial service to celebrate the life of his father, the sixth Duke of Westminster at Chester Cathedral, Chester. Picture: PA.Source:AAP

He has been snapped arm in arm with his girlfriend Harriet Tomlinson, who he is reportedly “blissfully happy” with.

The image, taken on a romantic holiday abroad, shows the pair grinning with glee, with wine glasses by their sides.

A source close to the duke told the Daily Mirror: “They have a lot of shared interests and are both very down to earth and ­family orientated.

“She’s a really lovely girl and very much the love of his life.”

The source added: “Hugh is happiest when he is enjoying time with Harriet and their close circle.

Harriet Tomlinson.Source:Supplied

“He was left crushed when his father died but Harriet has been a huge ­support and is helping him to get used to his new responsibilities.”

Hugh and Harriet, both 26, attended the private co-educational Ellesmere College in Shropshire together, which costs £30,000 ($48,671) a year.

Harriet also lived near the duke while growing up — she was raised in Chester, near Hugh’s 11,000-acre family estate, Eaton Hall.

She works as a consultant on the estate agency desk at recruitment firm Deverell Smith in the City of London.

She graduated from the University of Wales with a teaching degree four years ago, before going on to study public relations and event planning at University College London.

Hugh is believed to have whisked his new girlfriend away on a series of romantic getaways, including a luxury trip to California.

The young couple are believed to have stayed in the plush Ventana resort on the Big Sur coast, where rooms cost upwards of £500 ($811) a night.

Snaps shared online show the happy couple with their arms around each other, drinking wine and taking in the view, as well as the duke, who is godfather to Prince George, horsing around in front of a Ford Mustang convertible.

This article originally appeared on The Sun and was republished with permission.