The Conservative MP Philip Davies lobbied the government on behalf of a casino to introduce a measure that was then included in last week’s gambling white paper, it has emerged.

The MP for Shipley, in West Yorkshire, wrote in February to the culture secretary, Lucy Frazer, after being entertained at Les Ambassadeurs luxury casino in Mayfair, central London.

He asked Frazer, who was overseeing the shake-up of gambling laws, to make changes that would allow casinos to offer credit lines to gamblers, including “ultra-high net worth foreign visitors” playing the tables at Les Ambassadeurs.

This change was later included in the government’s white paper on gambling reform.

In his letter, Davies at one stage referred to the casino’s income as “our” revenue.

“I should also add that they are the only operator to contribute a market-leading 1% of our gross gaming yield [an industry measure roughly equivalent to revenue] to GambleAware,” he wrote.

Asked repeatedly by the Guardian if this apparent error was the result of him reproducing material provided to him by the casino, Davies did not answer.

Les Ambassadeurs said it had briefed Davies on the credit issue and had also “provided information to help inform his letter”.

Davies declined to provide an on-the-record statement but told the Guardian that he had written to Frazer because he agreed that Les Ambassadeurs should be allowed to provide credit.

His entry on the register of interests does not include any remuneration from Les Ambassadeurs and he is understood not to have received any.

Les Ambassadeurs confirmed it had hosted him for a tour on the 25 January and that he had enjoyed a meal at the club, whose website boasts of its fine dining options. MPs do not have to declare hospitality below the value of £300.

The letter to the culture secretary from Davies, a longtime gambling advocate who received £50,000 working for Ladbrokes owner Entain, was revealed in response to a freedom of information request by the Good Law Project.

Jolyon Maugham, founder of the Good Law Project, said: “Why do the interests of the gambling industry seem always to trump the public interest, herein proper safeguards?

“You sometimes wonder who the Conservative party are in government for, the public or the gambling industry?”

The government last week published a series of reforms that generally cracked down on online gambling but loosened restrictions on land-based casinos. While some campaigners welcomed the overhaul of laws passed under Tony Blair’s government in 2005, the white paper drew criticism for failing to limit advertising and for farming out many of its key proposals to a year-long consultation.

Davies has long advocated for the gambling industry in parliament and has also been one of the largest beneficiaries of money spent by the £10bn-a-year sector on politicians.

As well as earning £50,000 in one year advising Entain, he has received up to £14,713.60 of hospitality from betting and horse-racing firms over the past two years, including days out at Ascot and cricket Test matches.

Davies recently became co-chair of the cross-party parliamentary group on betting and gaming after his predecessor, Scott Benton, was suspended pending an investigation by the parliamentary commissioner for standards.

Benton was filmed by undercover reporters for the Sunday Times offering to lobby ministers on behalf of the gambling industry for up to £4,000 a month.