Ratcliffe asks Manchester United fans for patience as he seeks to bring back glory days

British billionaire will pay Glazer family £1.25bn for minority stake and will take charge of football operations

Sir Jim Ratcliffe outside Manchester United's Old Trafford stadium. PA

Sir Jim Ratcliffe has told Manchester United supporters it will take "time and patience" to bring back the glory days following his agreement to buy a 25 per cent stake in the club.

The British billionaire's Ineos group will pay owners the Glazer family around £1.25 billion for a minority stake in the Old Trafford club and has promised to inject around £300 million into its infrastructure.

Ratcliffe will take charge of the Red Devils' football operations once the deal is given a regulatory sign-off by the Premier League, which may take six to eight weeks..

The 71-year-old said in an open letter to the Manchester United Supporters Trust on Tuesday: "I believe we can bring sporting success on the pitch to complement the undoubted commercial success that the club has enjoyed.

"It will require time and patience alongside rigour and the highest level of professional management.

"You are ambitious for Manchester United and so are we. There are no guarantees in sport, and change can inevitably take time but we are in it for the long term."

After the deal was announced on Christmas Eve, Ratcliffe said: “As a local boy and a lifelong supporter of the club, I am very pleased that we have been able to agree a deal with the Manchester United board that delegates us management responsibility of the football operations of the club.

“We are here for the long term and recognise that a lot of challenges and hard work lie ahead, which we will approach with rigour, professionalism and passion. We are committed to working with everyone at the club – the board, staff, players and fans – to help drive the club forward.

“Our shared ambition is clear: we all want to see Manchester United back where we belong, at the very top of English, European and world football.”

United last won the Premier League in 2013 in Sir Alex Ferguson's final season before he announced his retirement.