Leslie was born in 1950, the son of Leslie Cooper and Elvie Hiscock.  He was baptised on the 4 February 1951 at St Cuthbert's, East Brunswick. The family resided at 44 John Street, East Brunswick when he was baptised.
Leslie almost drowned in Kororoit Creek, Deer Park, on the 19th of August 1952.
He grew up in Deer Park and attended the Deer Park Primary School and the Sunshine Technical College.
In 1969, Leslie joined the P.M.G.'s Department as a Techinian in Training.
In 1971, Leslie James Cooper married Elizabeth Jillian Myrwoda.
Les gained the position of Senior Technical Officer Grade 2 and remained employed at Telstra until his redundancy in 1994.
His post formal education had enabled him to gain a Diploma of Telecommunications Engineering.
In 1995, he gained a contracting position as an Installation Engineering Engineer at Ericsson Australia in Preston. Les remained in that position until his resignation in 2000. The Preston office was to be relocated to Broadmeadows, which was too difficult to commute to from Chelsea Heights.
Later in 2000, Les gained a contracting position with Nippon Ericsson K.K.. This meant relocating to Japan for 18 months. Due to the "Tech Crash" of 2001, his contract was not renewed.
He has travelled for both business and personal reasons, and has been to South Korea, The Netherlands, Thailand, Sweden, New Zealand, Germany, Japan, and China.
From 2004 until 2010, Leslie was a Education Services Officer (fancy name for a Teacher's Aid) at the McKinnon Primary School.
In October 2010, Leslie and Elizabeth relocated to Sea Lake, Victoria, Australia.
In September 2015, Les became interested in tracing his family tree and was able to build on the pre-internet research conducted by his maternal Aunt Mavis.
Leslie Cooper is a member of the Australia Project.
In 2016, Leslie discovered that he had inherited haemochromatosis aka the Celtic Curse, and in 2017 he was diagnosed with osteoarthritis.