[4][12] In 2006, Thomson Playford established a Sydney practice by merging with Cowley Hearne a North Sydney-based boutique founded in the 1960s.

[18][19][20] Prior to the 2014 merger with Herbert Geer, Thomsons experienced significant growth since 2009, with revenue and average profit per partner, tripling.

Between 1962 and 1970, three small practices were absorbed into Herbert Geer & Rundle; Farmer & Ramsay, William & Matthews and the office of Cyril Brooks.

The firm achieved publicity in the early 1970s by handling the defendant’s litigation for all workers' compensation claims arising from the West Gate Bridge collapse.

Further office relocations occurred with moves to Owen Dixon Chambers and BHP House before arriving at the State Bank Building in 1983 when the firm had 12 partners and 110 staff.

[25] Prior to the merger with Thomson Lawyers, Herbert Geer’s partnership had fallen by 28% from 53 partners to 38 in the preceding 3 years, due to lateral defections.

[23] In 2022, Thomson Geer successfully defended former Prime Minister Scott Morrison, the 46th NSW Premier Dominic Perrottet, Liberal Party federal president John Olsen and others in the Federal Liberal Party intervention regarding the management of its NSW Division.

Notably, the ruling of the New South Wales Court of Appeal is the leading precedent in Australia on the justiciability of disputes arising out of the constitutions of unincorporated political parties.