Last month licensing officers from the Royal Borough of Windsor and Maidenhead, supported by the Commission and trading standards, conducted age verification test purchasing at Royal Ascot.
Of the 17 operators tested seven allowed a 16-year-old to place a £5 bet and are now having their licence to offer gambling reviewed by the Commission.
Richard Watson, Commission Executive Director, said: “These licence reviews show how strongly we feel about underage gambling.
“Every single gambling business must protect children from gambling but the on course bookmakers results have remained unacceptable.”
Mr Watson said the on-course sector had a history of failing age verification exercises.
He said: “Despite various educational attempts to raise standards, by ourselves and the trade bodies, the on-course sector has historically performed poorly in both underage gambling test purchase exercises and Think 21 testing.
“Pass rates have failed to meet the standards expected and the sector has consistently performed to levels below those we see in other gambling and age restricted products. By way of example, over the past four years, the on-course sector has a pass rate of around 35% for Think 21 testing.”
“We recognise on course bookmakers are small businesses but we cannot allow them to disregard their responsibility to protect children.”
Mr Watson added: “We welcome the positive initiate by the local authority and the racecourse to raise standards in the gambling industry.”
Cllr David Cannon, Lead Member for Public Protection at the Royal Borough of Windsor and Maidenhead, said: “I am delighted that our officers led and organised this test purchasing. It is important that our residents as well as visitors to the borough, are kept safe. It is not acceptable to take bets from young people and I am pleased that strong action is taking place.
“Our hard working team of officers will often carry out test purchasing across the borough to ensure our residents are kept safe and that traders are abiding by the rules.
“I am pleased that this hard work is paying off and the Gambling Commission are taking action against those bookmakers.”