Purewal (pictured), who founded the business alongside Jon Lonsdale and Billy Hamilton-Stent in 2001, has sold his 25 per cent stake in Octopus to the other shareholders and departs at the end of this week.
Purewal said: "Octopus Group has been my focus for 18 years and I’ve loved it. I’ve learned a lot, we’ve achieved a lot and we’ve tried to evolve the agency PR offer across that time. Having established our ‘Brand to Sales’ approach and seen its success, and with Octopus in strong health and fit for the future, it’s the right time to dive in at the deep end of a new challenge.
"I want to bring the skills I’ve learned in the PR industry to play my part in helping people across society in taking better care of themselves without popping pills. This new project, Superfied, feels like a suitably big challenge."
Octopus CEO Lonsdale said: "Sandy is not just a founder and architect of Octopus Group but also a close friend. We’re all really excited for him in his new healthtech start-up and hope that he’ll become a client soon."
He added: "Sandy leaves Octopus Group in amazing shape, following a great 2018 where our ‘Brand to Sales’ proposition is really landing within the tech community."
Lonsdale said there would be no changes to the management team as a result of Purewal’s departure.
Octopus generated UK revenue of £4.8m in 2017, with a headcount of 57, according to the PRWeek UK Top 150 Consultancies report. Its clients include Red Hat, Marketo, Travelex, Blackberry and SSE.