"People tried very hard to do the right thing, it clearly has not worked," former chief executive Sir Terry Leah said in an interview to be broadcast on the BBC's Panorama programme tonight.
"In the end that's a failure of leadership, not a failure of the business, not a failure of the people who work hard every day."
"When you're the chief executive, if it goes well, you get credit, if it doesn't go well, you must take responsibility and Phil Clarke has taken that responsibility and paid the price with his job."
Philip Clarke's shock departure from the supermarket chain came after a string of poor results. It marked a particularly torrid year for Tesco which was rocked by a £250m profit overstatement, the suspensions of top execs and a grand total of five profit warnings.
Clarke had worked his way up to chief executive from the shop floor, finally taking up the position after Sir Terry Leah stepped down in 2011.
But Sir Terry Leah said Clarke had actually allowed Tesco to lose out on market share to its rivals.
"It's a big company, Tesco, and also very empowered - people were given responsibility and trusted to get on with their job, so there was a big team of experienced leaders."
"And too many of those were allowed to go in too short a period of time and so there was a shortage of experience, the kind of experience you need to carefully navigate a business like Tesco through this very turbulent and difficult period of this long, long recession, with these changes in structure of retailing taking place."