The register
The register lists Interpublic Group in London as a licensed sponsor on Global Business Mobility: Senior or Specialist Worker and Skilled Worker, 2 routes in all, and has done since at least 2026. Rating on the current register: Worker (A rating).
Companies House lists it as Interpublic Limited, number 00867637, incorporated 1965: 60 years of filings behind the name. The registered office is at Bankside 3 90-100 Southwark Street, London, SE1 0SW, SE1 0SW. By its SIC codes the business is in professional and technical services.
A licence says an organisation may sponsor; it does not say it is hiring today. The way to find out is the same as for any employer: the careers page, the job boards, and a direct approach with a UK-style CV that says early that sponsorship would be needed.