Like thousands of other foreign teachers in Britain, he is considered unqualified - even though he has a teaching degree and three years'
After doing a four-year teaching degree, the Australian science teacher easily found work at Gympie state high, a small-town secondary two hours north of Brisbane on Queensland's Sunshine Coast.
There, he was considered a competent classroom practitioner.
"It is quite a big school, 1,100 students, but in a small- town setting," he said. "Country kids can be a bit rough, so it could be a challenging environment to work in. They tended to get into a lot of fights."
To gain qualified status in Britain he must take the Overseas Trained Teacher Programme - or continue to be paid roughly pound;5,000 a year less than his UK colleagues.
Mr Gregory, who has been working at a secondary school in Westminster, central London, for four months, said: "The school seems to be happy with me - if they weren't they could ask me to leave at any time.
"It is frustrating. It does not make sense to expect a teacher like me to stand in front of a class just like every other teacher, but pay me less."
The 25-year-old, who takes home just over pound;400 a week, said that he was not aware that he needed QTS when he arrived in the UK.