Brewer began his 50-year career with marine insurancecompanySedgwick Collins in 1959.[5] In 1976 he went to Tokyo to open the Sedgwick Group's Japan office and lived there for three years. He set up its group office in China in 1981, obtaining the first broker's authorisation in 1993. He also opened the company's representative office in Bombay in 1986. He was non-executive vice-chairman of Marsh Ltd., the company which bought Sedgwick, from 2007 to 2009 and a director or consultant for various insurance companies. He was Chairman of the China-Britain Business Council until 2013 and held non-executive directorships of LIFFE Administration and Management (2009–2023), Tullett Prebon SITICO (China) (2006–2023) and the National Bank of Kuwait (International) (2007–2023).
^"Crown Office". The London Gazette. 2 June 2008. Retrieved 3 June 2023.
^"Birthday's today". The Telegraph. 28 May 2013. Archived from the original on 28 May 2013. Retrieved 24 May 2014. Sir David Brewer, Lord–Lieutenant for Greater London, 73
^"Obituaries" Trusty Servant. Winchester College. Nov 2023. p. 36. Retrieved 12 December 2023.
^"Lord mayor's Show"(PDF). The Worshipful Company of Blacksmiths. 12 November 2005. p. 5. Archived from the original(PDF) on 3 February 2011. Retrieved 10 February 2011.