Karren Brady has announced her decision step down as deputy-chair of West Ham and will leave the club.
Brady departs after 16 years, working with joint-chairman Daniel Kretinsky and David Sullivan on the board, to focus on other business interests and her role in the House of Lords.
During the 57-year-old Baroness' tenure the club completed their move from Upton Park to the London Stadium, which was built as the flagship venue for the 2012 Olympic Games.
Brady's exit sees the end of a near-40-year business relationship with Sullivan, who first appointed her in March 1993 at Birmingham City.
"It has been a privilege to work alongside the board, management, players, staff and supporters at West Ham United," said Brady.
"Together we have achieved remarkable milestones, but the highlight for me will always be lifting the UEFA Europa Conference League trophy - a moment that will stay with me forever.
"I am deeply grateful for the relationships, challenges and opportunities that have shaped my time at the club."
Joint-chairman Sullivan said: "Karren has been an exceptional leader and a key figure in the club's development over the years. We wish her every success in her future endeavours and thank her for her outstanding contribution over the past 16 years."
Your Site News chief reporter Kaveh Solhekol:
"It's been on the cards since the turn of the year. She's been thinking about leaving West Ham for quite a while, and has already said her goodbyes to people at the club last week.
"It is, nonetheless, very big news. She's the first lady of football, she's been a trailblazer and working in a male-dominated industry for about 40 years now, and has been one of the most powerful and high-profile figures in the men's game.
"How she'll be viewed depends on how you look at it. She'll argue she leaves the club in a better state than when she arrives - moving to the London Stadium from Upton Park, something she was at the forefront of negotiating and got a fantastic deal for West Ham.
"Under her watch West Ham have also won the Europa Conference League, their first trophy since 1980.
"But she has been a controversial figure, alongside David Sullivan and the late David Gold. A large section of West Ham fans are unhappy about the way the club has been run and the move to the London Stadium. They feel they should have stayed at Upton Park.
"As ever, there are two sides to the story. But I think most people, especially not West Ham supporters, would say she has been a significant figure in the past 20 or 30 years.
"She's someone who is very successful, she's got a lot of business interests and is famous for being on The Apprentice. I've always been struck by the fact at every Premier League shareholder meeting I'm covering in London, she's always there.
"If she wanted to stay in football, she would have lots of opportunities. But she is already someone very busy, and I'm sure will continue to have a packed diary."
