The expansion of the family farm in 1960, lead Mr Mann to work full time on the Tammin property.
During this time Mr Mann was also involved in football, both as a player, and in later years as a coach.
After farming in Tammin for 11 years Mr Mann moved to Scarborough and during this time he became involved in agriculture policy, having various positions with the WA Farmers Federation, the National Farmers Federation and member of the WA Wheat Quota Committee until 1979.
Between 1976 and 1983 Mr Mann was a board member for the Australian wheat board.
His involvement with the Australian grain industry continued throughout the 1980s, when he became president of the Australian Wheatgrowers Federation in 1979, and commissioner of the Industries Assistance Commission and Associated Commissioner for the Wheat Marketing Inquiry between 1986 and 1987.
In 1983 Mr Mann became an executive officer with the WA Farmers Federation.
His involvement in the rural sector in WA saw Mr Mann become member of the Advisory Panel of the Churchill Fellowship Awards for the Primary Industry and Rural Sector between 1981 and 1990.
Mr Mann was appointed rural policy advisor to successive premiers in 1984 to 1990 and senior policy officer to the Minister for Agriculture between 1990 and 1993.
His dedication to the WA Farmers Federation saw him regain his appointment as one of the organisation¹s executive officers in 1993 to 1995, and he was appointed deputy director of WAFF in 1995 for two years.
In 1997 Mr Mann semi-retired and started his own business consultancy in Rocking-ham.
He became inaugural chairman of the GLA in 2003 and remained in this position until 2006.
Mr Mann went back to farming in 2005, where he ran Boer goats on a small hobby farm in Toodyay.