Marcus was born in Minyip, Victoria, the only child of Reverend Jack and Vera Benjamin (nee Mills). Jack was the Methodist minister for that area, and this occupation meant that the family moved frequently. During Marcus’ early years Jack was with the AIF 8th Division as a Chaplain and was a POW in Changi. His name appears on the Chaplain memorial there.

His secondary education was completed at Melbourne Boys High School. He matriculated in 1949, and completed his medical degree at Melbourne University in 1955. During the next four years at the Royal Melbourne Hospital Marcus came under the guidance of Dr Alex Sinclair who told him that to be a good psychiatrist you first must become a physician. Marcus became a member of the College in 1962.

He married Gwen Harris in February 1961. They were life partners for the next 47 years.

Marcus was employed by the Mental Health Service, first at Ballarat, then Royal Park, and finally Larundel, becoming the youngest Psychiatrist Superintendent of Larundel in 1966.

In 1969, much to the good fortune of the Geelong Community, he, Gwen and their five children moved to Geelong to the Barwon Region. He was in practice there for 27 years.

Marcus was a large imposing person with a great intellect, many interests and a huge laugh. He was soon a leader among the doctors of Geelong. Nothing pleased him more than making medical diagnoses in his psychiatric patients. His practice was for all ages and all people. His Christian wisdom, along with his broad experience, often helped as much as any drugs.

In Geelong Marcus was Consultant to Dax House from 1973 to 1996, Director of the Child and Adolescent Unit Dax House from 1974 to 1978, and Dean of the Geelong Hospital Medical School from 1974 to 1977.

After retirement to Melbourne in 1996, Marcus discovered that there was no psychiatrist in Werribee, Victoria, so worked part-time there until just before his death. He died of multiple organ failure after a long history of renal disease.

Marcus had many interests apart from his work. He was always involved in his children’s activities, and both he and Gwen were very involved with the Methodist Church in Yarra Street, Geelong. They started Church in the Round for young people there, and this is still part of that Church’s activities. They both loved opera and had many trips to Covent Garden and the Metropolitan in New York during his 'retirement'.

Marcus was a great bloke, excellent company, and his resounding laugh was frequently heard in the consulting rooms that we shared for many years. His advice was freely given and always appreciated by all his colleagues.