The reforms mark a radical streamlining of the UK's third-largest shop by Matthew Bull, the South African drafted in as the chief executive earlier this year to put it back on course after a string of account losses and its failure to get on pitchlists.
The 60-strong board is being scrapped as part of Bull's effort to rid Lowe of bureaucracy. It will be replaced by a group of seven senior managers, including Bull and Paul Weinberger, the chief creative officer for Europe, who replaces Edwards as chairman.
They are joined by Jeremy Bowles, the managing director, and Mark Cadman, the client services director, who will also have the title of MD. Damon Collins, the executive creative director, Vince Squibb, the senior creative, and Eric McClean, the finance director, complete the line-up.
The changes are seen as an attempt by Bull to give the talent within the agency a chance, rather than go immediately for fresh blood.
Bull said: "Everyone on the management group has proved themselves to be a good leader or has the potential to be one. The only person in the group who hasn't proved himself is me."
Meanwhile, Joanna Bamford is being replaced as the planning director by her deputy, Russ Lidstone. She will continue writing strategies but have no management role. "I don't think Joanna is right to lead the planning department and neither does she," Bull explained.
One of Lidstone's first tasks will be to decide whether to assimilate Lowe Brand, the group's strategic consultancy, within the agency planning department.
Bull claimed he had dissolved the board because it had little or no authority for running the agency and had become little more than "a salary grading structure".
He also insisted that Edwards' decision to leave, two years after joining Lowe from the Henley Centre where he was the chairman and chief executive, was entirely his own. "I've tried to cajole him into staying but he's decided this isn't right for him," he said.
The long-serving Weinberger, described by Bull as "an icon of what's good about this agency and a good counsel for me", will continue to be involved in creative development of the Tesco business.
Bowles and Cadman - "I see both of them as future chief executives of London agencies," Bull said - will split client responsibilities between them. Cadman has had a long relationship with Tesco and Bowles with Stella Artois.