Paul Wicken and Stuart Humphries each scored twice for Canterbury with David Mathews and Hacker completing the rout. Bobby Crutchley claimed Cannock's 61st-minute consolation.
Southgate threw away their lead to go down 5-2 at Reading and with it lost the chance of taking over the leadership from Cannock.
In the relegation battle at Guildford, the home side shrugged off two early goals from Doncaster's Robin Benford to win 4-3, with Ian Jennings and Danny Hall each getting a brace.
Chris Ambridge's hat-trick in Havant's 3-0 win away at Bromley keeps them ahead of Surbiton on goal difference at the top of Division One.
In Saturday's women's National League, Slough, 5-2 winners against Ipswich, opened up a gap of five points at the top of the Premier Division, maintaining their maximum points record.
Woking also kept their 100 per cent record intact with a 2-1 win against West Witney, staying three points clear at the top of Division Two. With Canterbury drawing 1-1 with Chelmsford in Division One, Leicester - 5-1 winners against Bracknell with Sarah Blanks and Justine Williams each scoring twice - have a three-point lead.Reuse content