Three gambling businesses owned by William Hill will pay a total of £19.2 million for “widespread and alarming” social responsibility and anti-money laundering failures, the Gambling Commission has announced.

The “settlement” is the largest in the Gambling Commission’s history.

WHG (International) Limited, which runs williamhill.com, will pay £12.5 million; Mr Green Limited, which runs mrgreen.com, will pay £3.7 million; and William Hill Organisation Limited, which operates 1,344 gambling premises across Britain, will pay £3 million.

Gambling Commission chief executive Andrew Rhodes said: “When we launched this investigation the failings we uncovered were so widespread and alarming serious consideration was given to licence suspension.

“However, because the operator immediately recognised their failings and worked with us to swiftly implement improvements, we instead opted for the largest enforcement payment in our history.”

Social responsibility failures at William Hill businesses included allowing one customer to open a new account and spend £23,000 in 20 minutes, allowing another to open an account and spend £18,000 in 24 hours and a third able to spend £32,500 over two days – all without any checks.

Ineffective controls allowed 331 customers to gamble with WHG (International) Limited despite having self-excluded with Mr Green.

Anti-money laundering (AML) failures included allowing customers to deposit large amounts without conducting appropriate checks – one customer was able to spend and lose £70,134 in a month, another to lose £38,000 in five weeks and another to lose £36,000 in four days.