The failures at William Hill were so “widespread and alarming” that the gambling regulator seriously considered suspending its licence, it has said.
They included multiple instances when new customers were able to spend tens of thousands of pounds – one racking up £23,000 within 20 minutes – without any checks.
Another was allowed to open an account and spend £18,000 in 24 hours, while a third newcomer spent £32,500 over five days.
Failing to identify certain customers at risk of harm led to yet another customer losing £14,902 in 70 minutes, while one customer lost £54,252 in four weeks without the operator seeking any evidence of income or carrying out adequate checks.
These “insufficient controls” allowed a customer to open his account and lose £11,400 over the first 30 days, and another did not receive a telephone call from the operator until losses reached £45,800.
The failure to apply a 24-hour delay between receiving a request for increased credit and granting it led to a customer being allowed to immediately place a £100,000 bet when his credit limit had been set at £70,000.
And in a widespread failing of protections supposed to help gamblers impose limits on themselves, 331 customers were able to gamble with William Hill Group (International) despite having self-excluded from Mr Green, which is owned by the group.
Anti-money laundering failures included allowing customers to deposit large amounts without appropriate checks, with one customer 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.
Customers were able to stake large amounts of money without being monitored or scrutinised to a high enough standard, the Gambling Commission found, with the operator failing to request Source of Funds evidence when one customer staked £19,000 in a single bet.
No documentation was sought from a customer who staked £39,324 and lost £20,360 in 12 days, nor from another who staked £276,942 and lost £24,395 over two months.