Palmer will head the agency as its managing director, while Janes and Polkinghorne will work as its creative directors.
Sell Sell is already working on a campaign for 82ASK, the consumer text service that answers any question sent to it. It also has a brief for the S&M Cafe restaurant chain.
Palmer said: "Our focus is to create work that comes from the old-fashioned principle of selling a client's product. Matt, Vic and I have always shared this view of what makes for great advertising, so it seemed inevitable we would put this into practice by setting up our own place."
Polkinghorne added: "Ever since we entered the business, we've seen ourselves as salesmen with marker pens and thought that the best advertising is direct and charming. Nothing gives us a buzz more than producing campaigns for our clients that are commercially successful."
Janes, Polkinghorne and Palmer first met at St Luke's in 1999 where they worked on accounts including Clarks, Ikea and Travelocity. Janes and Polkinghorne left St Luke's in September 2003 and went on to work at Lowe, Karmarama and then Saatchis.