JIM Murphy is facing questions about his plan to end the 35-year-old ban on booze at football games after it emerged one of his oldest friends is a top lobbyist for the drinks industry.

The teetotal Scottish Labour leader announced in February that he wanted to restart the sale of alcohol inside Scottish grounds, arguing it worked well in England.

He launched a Labour consultation on the idea and held a club summit at Hampden Park.

But Murphy was last night accused of failing to mention a potential conflict of interest: his friendship with Kieran Simpson, global public affairs manager at brewers Heineken, which has drink deals with many English clubs.

Simpson, whose job involves working with governments on alcohol policy and legislation, was best man at Murphy's wedding.

The SNP said Murphy should have been upfront about the link when he championed drink sales, and should now say if he was lobbied on the subject.

Labour dismissed the suggestion of anything improper as "utter nonsense", while Heineken denied Simpson had had any discussions about alcohol at Scottish games.

Murphy and Simpson have known each other since their rise through Strathclyde University Labour Club in the 1980s and 1990s.

A Labour source described Simpson as Murphy's "right hand man" in their student days, when Simpson was chair of Scottish Labour students and Murphy was President of NUS Scotland.

"They came as a double act," said the source, adding they remained "close".

When Murphy entered Parliament as MP for East Renfrewshire in 1997, Simpson went to Westminster as a special adviser, or SpAd, in Tony Blair's first government.

Among his fellow SpAds at the time was John McTernan, now Murphy's chief of staff.

While Murphy climbed the ministerial ladder, Simpson stayed in the Whitehall background.

In 2002, he became head of public affairs at brewers Scottish & Newcastle, which became part of Heineken in 2008.

In January 1998, Simpson was best man at Murphy's wedding to primary teacher Lynda Cook.

Although he now works in the Netherlands, Simpson retains a house in Edinburgh.

Heineken is one of the world's largest brewers, with brands including John Smith's, Foster's, Strongbow, Newcastle Brown Ale and Murphy's stout.

The Dutch giant has big links to sport, spending around £55m a year worldwide on sponsorship, much of it on football, including a decade-long sponsorship of the UEFA Champions League.

Heineken also has deals to sell its brands at numerous English football grounds, including Manchester City, Leeds, Sunderland, Blackburn, Bristol City, and Middlesbrough.

Expansion into the Scottish market - if the law changed - would be a natural move.

Last October, Murphy saw the hospitality facilities at Manchester City for himself, when he received £850 worth of tickets from the club for a home game.

The booze ban at Scottish grounds has been in place since a riot between Rangers and Celtic fans at the 1980 Scottish Cup, though a similar ban at rugby stadia ended in 2007.

Denied to ordinary fans, alcohol can however be served in football corporate boxes.

When Murphy launched his campaign, he said "class prejudice" meant football fans were treated as "second-class citizens" and "all clubs" should be able to sell alcohol.

The announcement was criticised by medical experts, domestic violence groups, the SNP, Greens and LibDems.

SNP MSP Sandra White said: "Many people were surprised that Mr Murphy raised the marginal issue of drinks firms and clubs being able to make money from selling alcohol at grounds.

"Mr Murphy needs to be straight with the public and answer as to whether he was lobbied by any representative of the drinks industry to promote this issue."

Professor David Miller of Spinwatch, which monitors the lobbying industry, said: "It's a conflict of interest and he [Murphy] should have been more transparent. I think he should now give an account of any meetings with this guy."

A Heineken spokesman said: "Mr Simpson is employed by the Heineken global corporate affairs team and has been based in Amsterdam for the last three years, where he also lives.

"He does not work on our UK public affairs programme, and whilst he knows Mr Murphy socially, and as a former colleague, he has not spoken to Mr Murphy in any capacity since moving to Amsterdam.

"The Heineken UK business has not held any meetings with Mr Murphy on this matter or made representations to him. We have chosen not to take part in the [Labour] consultation exercise and remain neutral on the potential outcomes."

Labour spokesman said: "This is utter nonsense. Good, investigate newspapers like the Sunday Herald must wonder why the SNP are peddling crazy conspiracy theories.

"The real question is why the SNP are trying to ditch their core election demand for full fiscal autonomy. Can it be because Scottish Labour has proved it will cost Scotland £7.6bn?"