For the year to March the privately-owned gambling company, based in Stoke-on-Trent, paid £421m to its highest-paid director, who is understood to be Coates.

The payout excludes her share of a £95m dividend, more than half of which in previous years is thought to have gone to Coates, who is a majority shareholder. Her pay is thought to be approaching the combined total of what all FTSE 100 bosses were paid last year.

According to the latest report released by the High Pay Centre, the mean of chief executive pay across almost all the FTSE 100 was £4.7m.

A large proportion of Ms Coates’s fortune is reportedly put towards good causes, including Douglas Macmillan Hospice and Alzheimer’s Research UK. In the past few years, she has been building a 52-acre “modern country estate”, designed by Lord Foster of Thames Bank’s company, which specialises in giant commercial projects such as Kuwait airport.

The project managers for her estate built the gates for the New Panama Canal in 2016.Coates was named Britain’s highest taxpayer by this year’s Sunday Times Tax List. The share of Bet365’s taxes, plus HM Revenue and Customs’ charges on her pay and dividends, was £573m in 2019-20.

Mr Coates was considered a charitable woman who helped schools and charities with generous donations when she lived in a barn conversion that was fairly modest considering her wealth.

However, this changed in 2017 when she started acquiring country houses and farmland near Stoke to build a private estate. 

Ms Coates’s latest pay beats her previous record when she paid herself a £277m salary and about £46m in dividends for 2019, and also overshadows the £343m paid to the hedge fund manager Sir Chris Hohn last year. That was believed to be the highest annual amount ever paid to an individual in modern Britain, The Times reports.

Bet365 has acknowledged that it takes bets from “grey markets”, untaxed or unregulated jurisdictions where profit margins are higher, but it will not indicate if these include China. The firm has gambling licences in 14 countries, including the US and Australia.

Luke Hildyard, director at the High Pay Centre, said that a payment of hundreds of millions of pounds had “questionable value as an incentive to somebody already worth billions”.