Johnston and director Paul Murray were removed from their posts by new owner Craig Whyte on Monday night, with the news being announced to the Stock Exchange yesterday morning.
It also emerged from the meeting of the board that chief executive Martin Bain and director Donald McIntyre had been suspended by the club pending an internal inquiry.
There was little surprise about the dismissal of Johnston and Murray. Life-long supporter Johnston had been critical of Whyte during the recent takeover process and Murray had been behind a proposed rival buy-out bid.
Johnston said: "Myself and 26,000 other shareholders need to remain vigilant to ensure he (Whyte] remains committed to the club and honours what he said he would honour." From his base in the United States, Johnston said that he will now return to being simply a member of the Rangers Supporters' Club in Cleveland, Ohio.
"I feel there was unfinished business shepherding the club into the new era so from that point of view, it is mission accomplished," he said. "I will enjoy going back to being a fan again.
"I will be going to the Rangers convention in Orlando in June, I will be there with the Cleveland Rangers Supporters' Club, and I look forward to that.
"I am still not convinced he (Whyte] has an appreciation of the responsibilities and obligations to the club but I am optimistic about the club's future if he does what he says he is going to do. I truly hope he is going to be successful.
"And, as I said earlier, the next time we see a photograph of him holding up the SPL trophy, let us all hope that he has earned the right to do it."
Whyte's camp has refused to comment.