Sir James Dyson, the man behind the bagless vacuum cleaner, is the richest person in the south west, according to The Sunday Times Rich List 2014.

With his fortune remaining unchanged at £3billion this year, he is one of 104 British billionaires to be included in this year’s Sunday Times Rich List, which is published in a special 116-page edition of The Sunday Times Magazine on Sunday.

Nationally Sir James is joint 29th richest, says the 26th annual Sunday Times Rich List. The top 21 in the south west are worth £14.329bn collectively.

Sir James is planning to double the size of his research facility of his Malmesbury HQ at a cost of £250m, taking on 3,000 extra staff.

One of his latest inventions, the Airblade Tap, a combined tap and hand dryer, took 125 engineers four years and £40m to develop.

Sir James is said to have created 5,127 prototypes of his dual-cyclone vacuum cleaner before he perfected it. He recently pledged £20m to his James Dyson Foundation, with £8m of that going to the University of Cambridge to improve its engineering facilities.

Second and third in the list are behind the Hargreaves Lansdown financial advice organisation. Peter Hargreaves and Steve Lansdown are ranked second and third in the southwest wealth stakes with fortunes of £2.39bn and £1.45bn respectively.

Hargreaves, who lives in Somerset, recently stepped down as chief executive of Hargreaves Lansdown but retains a £2.24bn stake in the business.

Last December he gave shares in the operation worth just under £1m to charity. Lansdown owns League One football club Bristol City and Bristol Rugby Club through his Bristol Sport operation. In March he sold £200m of shares in Hargreaves Lansdown.

Another new billionaire in the region, who has seen his wealth more than double in the past year, is Chris Dawson, the man behind The Range discount chain, which will soon have more than 100 outlets nationwide.

His wealth has climbed from £585m last year to £1.28bn this year, a gain of £695m in 12 months. The stores are expected to make an £88m profit this year.

Retail success has also propelled Julian Dunkerton back up the southwest Rich List. The Superdry brand began with Dunkerton selling clothes in London from bin bags after he borrowed £2,000 from his father to start the business.

SuperGroup is based in Cheltenham and Dunkerton’s stake in the business is worth £445m today. Dunkerton’s overall wealth of £478m ranks him eighth in the region after a £281m gain in the past 12 months, up 143 per cent.

The 26th annual Sunday Times Rich List is published on May 18 in a special 116-page issue of The Sunday Times Magazine, which profiles the 1,000 richest individuals and families in the UK and the wealthiest 250 in Ireland.

The list is based on identifiable wealth, including land, property, other assets such as art and racehorses, or significant shares in publicly quoted companies. It excludes bank accounts, to which the paper has no access.

The Sunday Times Rich List 2014 is compiled by Philip Beresford and edited by Ian Coxon.