Richard Riddell, ‘Smirke, Sir Robert (1780–1867)’, Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, May 2010 accessed 27 May 2017. THis is a subscription site but access is free to readers of British libraries whose library subscribes.
Census of England 1841 (Warren House, Great Stanmore, Robert Smirke aged 60, architect.
Census of England 1851 (Italian Villas, Cheltenham, Robert Smirke, knight, aged 70 born London. Head of household, married. Living with wife, brother Edward and five servants)
Census of England 1861 (20 Suffolk Lane, Cheltenham, Robert Smirke aged 80, knight and landed proprietor, born Marylebone, London. Head of household, living with wife and married daughter, Laura Lambert and her daughter, Agnes)
National Probate Calendar (7 May 1867 Sir Robert Smirke died 18 April 1867 at 20 Suffolk Sq., Cheltenham, Gloucestershire. Effects under £90,000 probated to Edward Smirke of 18 Thurloe Sq, Brompton, brother, one of the executors)