The appointment of Lomas was confirmed as expected at a media conference but Brown surprised as he revealed his 25-year reign had come to an end.

Brown will be succeeded by son Steve and his last act as chairman was to introduce Lomas as manager.

The 37-year-old has signed a two-and-a-half year contract after impressing the Saints board with his leadership skills and enthusiasm.

Lomas said: "I'm delighted but I have mixed emotions with Geoff stepping down.

"I thought it was something I said in negotiations."

Lomas revealed he had spoken to predecessor Derek McInnes, who left for Bristol City, and previous boss Owen Coyle before accepting the offer.

"They said they are very loyal to the managers which is something, as a player of eight and a half years with Man City and West Ham, which is part of my ethos."

Lomas, who will be assisted by former international team-mate Tommy Wright, left his post as West Ham reserve coach to take up the role.

"It's the right time," he said. "Even when I was playing I wanted to be a manager. The way I played, I was captain at most of my clubs.

"I never sat about waiting for it to happen. I have done my licences and courses and got experience at non-league level.

"I coached the youths at Norwich and the reserves at West Ham. I had a couple of offers before this but I feel this is the right club."

Outgoing chairman Brown revealed the keen interest Lomas had shown in the job had encouraged the board to open talks before taking the unanimous decision to appoint him.

Brown held talks with Sligo Rovers manager Paul Cook early in the process but they broke down over personal terms.

Brown said: "I have stated through this process that I would consult the board and make sure the board was happy with the appointment.

"I have now decided that, as of today, I will stand down as chairman. Steve [Brown] will be my successor.

"The manager will have a one-to-one relationship with Steve. I have never been a believer in committees and boards.

"I believe in one-to-one relationships and I believe St Johnstone have done well with that in the past."

Lomas takes charge of his first match when Aberdeen visit McDiarmid Park in the Clydesdale Bank Premier League on Monday night.