Sir Martin Sorrell: "We continue to grow". Analysts urge caution, but WPP founder Sir Martin Sorrell is pushing ahead with his new empire, S4Capital. Talking to someone who has no time for small steps. You need to be logged in to view this content. Please Log In. Not a Member? Join Us Annual subscription "Online CHF 72.00 incl. VAT Add to cart 3 month subscription "Online CHF 18.00 incl. VAT Add to cart