The register
The register lists SEI Oxford Office Ltd in Oxford as a licensed sponsor on Skilled Worker, an entry that goes back to at least 2026. Rating on the current register: Worker (A rating).
Companies House lists it as Sei Oxford Office Limited, number 04404220, incorporated 2002: 24 years of filings behind the name. Registered office: Oxford Eco Centre Roger House, Osney Mead, Oxford, Oxfordshire, OX2 0ES, OX2 0ES. Its filed activity puts it in professional and technical services.
For a candidate this means one less obstacle: SEI Oxford Office Ltd already has the licence most employers would have to apply for. The rest is the ordinary job of getting the interview.