Change of party leader (Cosgrove): Beginning of Brooker's period in office: 'In December 1947 a Royal Commission led to criminal charges for bribery and conspiracy being laid against Cosgrove. On 15 December caucus elected Brooker leader pending a decision on the charges, and on 18th Cosgrove resigned and Brooker was commissioned', Hughes and Graham, p. 264, (see 'Sources', below); see also Townsley, pp 34-36 (see 'References', below). Brooker became Premier of a Labor Party majority government which lasted for two months.
Change of party leader (Brooker): 'Following Cosgrove's acquittal on 22 February 1948, Brooker resigned. Caucus elected Cosgrove leader on 25 February, and he chose a new ministry', Hughes and Graham, p. 264 (see 'Sources', below). Cosgrove was recommissioned as Premier of an Australian Labor Party majority government on 25 February.
References: For background on the period of postwar politics in Tasmania, see W A Townsley, Tasmania: Microcosm of the Federation or Vassal State, 1945-1983, pp 25-41, (Hobart: St David's Park Publishing, 1994), and note Terry Newman, Tasmanian Premiers 1856-1988: A Biographical Handbook, (Hobart: Tasmanian Parliamentary Library, ).
For a survey of Brooker's career, see R P Davis, 'Brooker, William Edward (1891 - 1948)', Australian Dictionary of Biography, Volume 13, p. 265, (Melbourne: Melbourne University Press, 1993), on line at: http://www.adb.online.anu.edu.au/biogs/A130300b.htm?hilite=Brooker
'Ministries: Names of the Members of Successive Ministries which have held Office in Tasmania since the inauguration of Responsible Government, together with the Dates of Appointment and Retirement', Journal of House of Assembly, Second Session of the Forty-Fifth Parliament of Tasmania, Anno LIII and LV Eliz II; Session 2 of the 45th Parliament, Volume 251, 2004-2006, (Hobart: Government Printer, Tasmania); Colin A Hughes and B D Graham, A Handbook of Australian Government and Politics 1890-1964, (Canberra: Australian National University Press, 1968, SBN 708102700), and the website of the Parliament of Tasmania, http://www.parliament.tas.gov.au/