[3] Graduated from Marion High School with a scholarship to attend the Royal Military College, Duntroon in 1971.

Master of Arts (History) from the University of NSW in 1985 with a focus on Australia's relations with the United States of America and South East Asia.

In 1993 he was posted as commanding officer of the Australian contingent in the 11 nation Multinational Force and Observers (MFO) in Sinai, Egypt, also serving as Assistant Chief of the 3,200-man force which monitors the peace agreement between Israel and Egypt from Gaza to the Gulf of Aqaba.

[5][6] Hamilton-Smith left the Army in 1995 to build a property development, investment and private child care centre business which had been first established in 1989.

The preselection victory of Hamilton-Smith prompted Brown to complain of interference by federal conservative faction MPs Nick Minchin, Grant Chapman, and Andrew Southcott.

However, Newspoll saw Labor back in a winning position on 54 to 46 in late 2008, and then 56 to 44 in early 2009 along with a widening gap in the Preferred Premier rating.

[14] However, this did not play out at the 2009 Frome state by-election sparked by the parliamentary resignation of former Premier Rob Kerin, which saw a rare two-party swing from the opposition to the government, and resulted in independent Geoff Brock taking the seat from the Liberals on preferences.

[15][16][17] Hamilton-Smith accused Labor of accepting split donations from the Church of Scientology based on information sent to the Liberal Opposition that was subsequently found to have been forged.

[27][28] Williams, Isobel Redmond, and Iain Evans ruled out contesting the ballot, with Hamilton-Smith and his moderate deputy Vickie Chapman the only contenders.

Brock agreed to support the Labor government on confidence and supply while retaining the right to otherwise vote on conscience.

[36] On 27 May 2014, more than two months after the election, in a media conference with South Australian Labor Premier Jay Weatherill, Hamilton-Smith announced his decision to resign from the South Australian Liberal Party to become an "Independent Liberal" MP, and to join the Labor cabinet as the Minister for Trade, Defence Industries and Veterans' Affairs.

[39] Labor unexpectedly won the 2014 Fisher by-election by five votes, following a 7.3 percent swing, which gave them majority government.

Major achievements over four years as a minister included helping to retain $90 billion worth of submarine and shipbuilding work in SA,[41] establishing Investment Attraction South Australia,[42] construction of the Centenary of ANZAC Memorial Walk along Kintor Avenue,[43] hosting the International Space and Astronautical Congress in Adelaide as Australia's first space industries minister,[44] and improving communication of small business through the establishment of a small business roundtable.

While serving as Leader of the Liberal Opposition, Hamilton-Smith led the debate to move football from Westlakes to the city, resulting in the redevelopment of Adelaide Oval.