He immediately showed his passion for, and made his mark in, sports medicine across Northland.
That love never left him, which is demonstrated in the list of his achievements, which include being the North Auckland rugby team doctor for 34 years, being involved in the care of Northland sportsmen and sportswomen in a wide range of other sporting codes including swimming, athletics, soccer, hockey, cricket, cycling and netball, having his sports medicine skills noticed at a national level, in the late 60s becoming the New Zealand soccer and hockey doctor, and serving as the New Zealand Olympic team's director of medical services at the 1982 Brisbane Commonwealth Games, the 1984 Los Angeles Olympics and the 1986 Edinburgh Commonwealth Games.
Of his career highlights, Marshall said "obviously rugby and Northland rugby" stood out, however, he added that going "overseas with New Zealand sports teams" was also a big achievement.
In the early 1960s, Marshall also became a founding member (and is now a life member) of the New Zealand Sports Medicine Federation, now Sports Medicine NZ. He is held in such high regard by this organisation that the keynote lecture at the annual NZ Sports Medicine Conference is still named after him.
In later years, as drug testing became more and more ingrained in all sport, he was recognised as the pioneer of drug testing in NZ and subsequently travelled the world, attending many international sports competitions in his capacity as a drug-tester and giving keynote lectures on the subject.
In 1994 he was awarded the prestigious Brian Maunsell Memorial Service to Sport trophy at the Northland Sports Awards and this service was also recognised nationally when he was awarded a NZ Honour for Services to Sport in 2006.
In 2012 Marshall became only the 23rd Legend of Northland Sport, Northland's version of a Sports Hall of Fame, placing him amongst the highest achievers and contributors to sport in the region.
A founding board member of Sport Northland in the early 90s, he became deputy chairman in 1998 before retiring from the board in 2001.
He was one of the driving forces behind Sport Northland's redevelopment of the ASB Leisure Centre in the late 90s, finally seeing it come to fruition years later.
For the past 14 years he has been Sport Northland's patron, which ended at the recent 2015 AGM when he declined to make himself available for re-election.
The Sport Northland board was delighted to offer former long-standing chairman Richie Guy the Patron role, which was duly ratified at the AGM. Guy was chairman of the Sport Northland board for over 20 years through until 2014 and is a former All Black, former chairman and now life member of the NZ Rugby Union, as well as the manager of the famous All Black side that won the first ever Rugby World Cup in 1987.
Other changes to the board included the retirements of James Morris (11 years on the board), and Angeline Waetford and Craig McKernan (both six years on the board).
Two new trustees were elected at the AGM by the member organisations - Anne Cooper, principal of Whangarei Girls High School, and Eru Lyndon, regional commissioner for the Ministry of Social Development in Northland.