The 60-year old has been a number two for all of his coaching career and has joked that perhaps the right job might come up when Fergie eventually retires from his post at United.
Brown, who has been Jim Jefferies' right-hand man since the late 1980s, has joined Colin Calderwood at Easter Road and admits he has never been in a position where he has been available to take a full managerial role although he would love to get the chance to take the reins of a club.
"I certainly don't think I'm a born assistant manager," Brown told The Scotsman. "All the time I've been wanting to be a manager, but there's never been a job that has come around that has been better than the job I've been in.
"But I still have ambitions of doing that. In football you've got to. Working with Jim gave me the freedom of doing a lot of things on the training park and tactically and I was satisfied doing what I was doing. But at no stage, ever, have I not had the ambition to be a manager, and I still have."
And Brown quipped that maybe one day he could step into the enormous Old Trafford shoes of Ferguson, even if it's in 15 years or so.
"It might come when I'm 75, right enough, but I still have the ambition. I think you've got to," he added.
"Although I'm the assistant manager I'm very much my own man as well. I would only do the job if it was giving me satisfaction.
"But if Man United want to appoint me if they're getting rid of Alex Ferguson then I'd certainly accept it."