But a doubt over their long-term tenure of the business arose this week as the supermarket refused to rule out Clemmow Hornby Inge as its eventual home.
Waitrose confirmed growing speculation about the future of its account on Friday, when it told Banks Hoggins O'Shea/FCB that it was ending their seven-year relationship. The business had been expected to follow Hoggins and O'Shea into HOW, which the pair set up in April along with Mark Wilson, the former Waitrose account director at BHO.
However, Mark Price, the Waitrose selling and marketing director, refused to rule out a link-up with CHI. "I'm not saying 'yes', and I'm not saying 'no'," he commented.
HOW's formation fuelled speculation that Waitrose would be its first client. But Price, who said he had spoken to three agencies and seen presentations from two, insisted he was in no hurry to make a decision.
"Chris and Ken are very good at what they do and we'd like to capitalise on their skills and experience," he added. "But it might be difficult for them to provide the plethora of work that we would need."
Industry sources say that CHI, currently winding down its relationship with Safeway, is likely to take on brand advertising, with local tactical work being handled in- house.
CHI and HOW were unavailable for comment.