He began teaching there five years ago on a succession of fixed-term contracts.
"There was a sessional contract here and a fixed-term contract there," he says. "The main problem was that at the end of the academic year you didn't know whether you were going to be employed again.
"In fact, the post I considered to be my post - because I'd been doing it for two years - came up again and I didn't get it. For me, that was a very uncomfortable moment.
"Fortunately, the department was eventually able to cobble together enough bits and pieces to bring in a reasonable wage."
But now Mr Marchant's job has been upgraded to a permanent post and is now employed on a 0.8 fractional contract, which means he works four days a week.
Canterbury College has recently made a shift from short, fixed-term contracts to more permanent ones.
"I think Canterbury college's attitude to part-time staff is actually pretty healthy," he says.
Mr Marchant, who has three teenage sons, now earns pound;22,000 a year pro rata.
He spends 0.5 of his timetable as a co-ordinator and 0.3 as a lecturer.
His spare day is used for writing and computer-aided composition.
"I think it is really important for people in our profession to keep their hand in," he says.