His son Kenneth became the school's third Headmaster — a position he held until joining the Royal Canadian Navy two years later; he died in a car crash in 1966.
Jack Eastwood Matthews was appointed as the next Headmaster and over the next seven years the school expanded in numbers and in international reputation.
In 1969, Prince Philip, Duke of Edinburgh, visited and presented Gold, Silver, and Bronze Awards.
It was called the McLaughlin-Osler Centre and was opened by former Old Boy, Teacher and then Peterborough MP Hugh Faulkner.
The next Headmaster, John Terry M. Guest was appointed in 1971, and Ashelworth House and property surrounding the school was purchased.
Although there was much debate among its alumni, Board of Governors, and trustees, LCS became co-educational in response to changing times and enrollment.
Under Hadden's headship, the old chapel was replaced (1997), an artificial outdoor ice hockey rink was constructed (2005) in memory of Bob Armstrong, the Northcote campus was added (2007) and construction on a $12.5 million Student Recreation Centre was begun (2007).
In early 2008, David Thompson, the Principal of Greenwood College School and LCS trustee, was appointed as Hadden's successor.
[citation needed] Struan Robertson joined LCS as Head of School in March 2012.
[8] LCS has a 315-acre (1.27 km2) wooded, waterfront, campus on the east shore of Lake Katchewanooka in rural Ontario.
It is just north of the village of Lakefield, an hour and a half drive north-east from Toronto, Ontario.
An outdoor artificial ice surface, The Bob Armstrong Rink, has been operational since November 2005.
Each student has an academic advisor who assists with all facets of the student's career at LCS (e.g., arranging extra help, including tutoring), and also a guidance counsellor who helps with course selection and university admission.
In 2015, an independent investigation found that Anglican pastor Keith Gleed (1932–2001), who worked at the school from 1974 to 1980, sexually abused young boys enrolled at Lakefield.