SIR James Dyson has maintained his standing as the richest person in the South West after seeing his fortune over the past 12 months shoot up by £500 million to £3.5 billion.

The inventor of the bag-less vacuum cleaner, whose HQ is in Malmesbury, has now risen from the joint 29th richest person in the UK to the 22nd wealthiest in the nation.

Dyson’s rising fortunes were revealed over the weekend in the 2015 Sunday Times Rich List which shows the 1,000 richest people in Britain.

It conforms that Dyson’s business, now worth £3bn, has gone from strength to strength after it took him 15 years to get his original bag-less vacuum cleaner on the market.

His latest product, the Dyson 360 Eye robot, was recently unveiled and engineers are working on technology that could double the life of smartphone batteries.

Keen to encourage the next generation of design engineers, Dyson, 67, is pouring money into higher education.

Last month, he gave £12m to Imperial College London to fund the Dyson School of Design Engineering, while last year he gave £8m to the University of Cambridge.

In addition to his £3bn business, Dyson has land holdings amounting to 25,000 acres and an 18th-century manor house, Dodington Park, in Gloucestershire, taking his fortune to £3,500m in all.

Somerset-based Peter Hargreaves and Steve Lansdown, at second and fourth respectively in the South West Rich List, have both seen their overall wealth decline in the past 12 months.

Hargreaves, 68, is down £496m and Lansdown down £157m as a result of a decline in the overall value of the financial group they founded together.

Hargreaves Lansdown is worth close to £5.6bn with Hargreaves’ current stake adding up to £1,824m, and Lansdown holding £902m-worth of the stock.

Lansdown, 62, formed Bristol Sport, bringing together Bristol City football club, newly promoted to the Championship, and other sports, including Bristol Rugby, the city’s rugby union side. His son, Jon, is the managing director.

The region’s third richest person is Chris Dawson, who has added £370m to his fortune in the past 12 months off the back of the continued success of his Devon-based home-and-garden discount chain, The Range.

A former market trader, Dawson opened his 100th store in Plymouth two months ago. There are now 110 stores within the business, which is valued at £1.5bn. Other assets and property lift Dawson to £1,650m.

Britain's wealthiest man is Len Blavatnik, worth an unbelievable £13bn. The London-based Ukrainian businessman jumped from fourth last year after seeing his wealth rise by more than £3 billion, according to the list.

The 57-year-old's company Access Industries invests in a wide range of areas, from oil and coal to telecommunications and real estate.