Mr Mullen – who scooped £4.8-million in 2011 with his wife Sue – is an avid Mariners fan and has been working closely with the club this season.
In January, his generous donation helped make the double signing of Gregor Robertson and Christian Jolley possible, while he also made a £10,000 donation to help ensure the club had the best possible preparation for the Play-Off Final at Wembley against Bristol Rovers.
Lee received the news at a board meeting today and is delighted to be opted onto the board. He said: “I said to John (Fenty) it is like being a player and to get the chance to deal with the running of the club, I'm really pleased about it.”
Asked if he would change anything, Lee said: “I would change nothing. It was down to a refereeing decision at Wembley.”
He continued: “I think I bring my leadership skills from the forces and my enthusiasm to promote the club at the team.
“Personally I think we are going to do really well this season. I think it is a shame that we lost Lenny and Carl Magnay, the Football League was too much of a pull for them. But I am confident that Paul Hurst will bring in good replacements. I think he will do his best to bring in the right players to get us promoted. As I've said all along, Paul is the best manager in our league.”