Those with a statistical bent can refer to the trebling in the company’s profits over his tenure and to the number-one spot he stole from Unilever’s Paul Polman in Aberfield Communications’ latest ranking of the most influential FTSE 100 chiefs.
Then there is the verdict from someone who was there when King arrived at the suffering company in 2004, having experienced the dog days after it lost its number-one status to Tesco in the mid-1990s.
Pip Wood, who King soon promoted from media relations head to external comms chief, recalls him setting the tone on his first day by going to a store to meet staff before coming into the head office.
"It said volumes about where he saw his focus needed to be," she says. "He was adamant that we had to tell the staff things before the outside world whenever possible, even if it wasn’t very convenient. It wasn’t working like that beforehand."
As well as being "a phenomenal communicator" he is "absolutely switched on to PR", claims Wood, now director of corporate comms at British Land after leaving the retailer in 2009.
"It’s fantastic to have somebody like that at the top of a company. You would put forward an idea to him and he would know exactly where you were coming from and you would have support at the top level."
Despite this, it is worth noting King has not taken the step of elevating a comms person to the executive board during his tenure.
However, the importance of not keeping staff in the dark carried through to Wednesday’s announcement that he would step down in July and would be replaced by group commercial director Mike Coupe.
Such sensitive news has to be conveyed to the stock market first, explains RLM Finsbury partner Jenny Davey, who leads the agency’s work on Sainsbury’s financial PR, but she points out that while other companies might have put the RNS out at 7am, the retailer opted for 9am and notified staff immediately afterwards.
Within the company, director of corporate affairs Alex Cole is pleased there were no hitches or leaks in what she calls "one of the most challenging pieces of comms from a corporate perspective, because it’s complex, involves individuals and there’s a duty to disclose pretty quickly while keeping the circle of people who know about it pretty tight".
The communications effort included an email from King to the company’s 157,000 staff, speeches in the head office atrium, and updates, images and video posted on the company’s corporate site as well as a media call and broadcast appearances.
Sainsbury’s clearly feels comfortable stressing the continuity of appointing Coupe, who has worked at Sainsbury’s since 2004 and with King for 17 out of the past 20 years.
While Coupe is an unknown quantity to most outside the company, there are certainly signs that the ground has been prepared. In 2010 he was given responsibility for marketing in addition to trading, IT and online.
A trawl of the Sainsbury’s corporate website shows a step up in the number of blogs authored by Coupe in 2013, including a King-like missive to staff on "the value of values" that is a broadside to Tesco over food provenance.
However, corporate history is peppered with uncomfortable transitions and one senior PR agency figure with extensive in-house experience warns off the record that "it is always an awkward phase as the old king’s power wanes and the new king wants to get into position".
While King sees out his time and fields the "what next" questions, Coupe will be deciding how best to take the spotlight when his superior exits the stage.
He is not booked to do any broadcast interviews, according to Cole. "The news is this is going to be happening rather than it has happened, so it is not appropriate to do anything further at the moment," she says.
"The media always wants you to go further. They always want to know what is going to happen next. You have to have a clear sense of what it is you want to communicate and whether it is the right timeframe."
Coupe himself might wish that Sainsbury’s run of growth was looking less vulnerable. After his promotion he told journalists he "hoped to continue Sainsbury’s successful formula but the market dynamics are changing and we may have to think differently at some point".
His lot is to deliver further growth while being measured against the standards set by the man who achieved the turnaround.
"King’s ability to communicate well to a range of audiences will be a tough act to follow," the agency figure believes. "As a communicator, the new man should be brutally honest with himself about what his strengths are and stick to the medium that he feels comfortable in. And the comms department shouldn’t try and make him do the same things that King did."