Dr. Sinclair was the founding member of the Saatchi Synagogue and continues to be closely involved as a Trustee. He was Chairman of Jewish Continuity, founded by the Chief Rabbi in 1993, and some years later, he oversaw its merger with the JIA, becoming Vice-Chairman of the newly formed United Jewish Israel Appeal. He continues to sit on the Board today. Dr. Sinclair was a founder of Schools J-Link, the Jewish Learning Exchange and the Jewish Outreach Network. He has been Chairman of the Management Committee of the Sage Nursing Home since its opening. Dr. Sinclair is Chairman of the Executive Board of The World Council for Torah Education and a Board Member of the British Friends of Arad. He is Vice Chairman of JNF UK.