Tregear reorganised the degree programs and appointed leading scholar-performers to the school, including Paul McMahon, David Irving and Erin Helyard.
[10] As a conductor, Tregear has co-founded two ensembles (IOpera[11] and The Consort of Melbourne,[12]) and mounted several world or local premieres and revivals of historic and neglected operatic repertoire, including the first modern revival of Samuel Arnold and George Colman's 1787 anti-slavery comic opera Inkle and Yarico, the first UK performance of Max Brand's opera Maschinist Hopkins at the Queen Elizabeth Hall in 2001,[13][14] the complete revival of Anna Amalia's Erwin und Elmire in Gotha, Germany[15] and the Australian premieres of Jonny spielt auf[16] and Rothschild's Violin[17] in Melbourne.
[23] In April 2024 Tregear mounted and conducted a bicentennial performance of Ludwig van Beethoven's Missa Solemnis at St Paul's Cathedral, Melbourne.
Tregear was described by the Times Higher Education in 2021 as a "transparency advocate"[35] for his work campaigning for universities to be more open and accountable about their finances and integrity processes.
[42] He was awarded the Medal of the Order of Australia (OAM) in the 2020 Queen's Birthday Honours "for service to music education and professional societies".