In Romania, firefighters go through a two-day training exercise, the emphasis is on speed.
"Speed was their first imperative, as opposed to their safety or the casualty's injuries," he said.
To his horror, the firefighters were so rushed, they almost injured their casualties – and each other.
"They would just break windows without putting any protection in for the casualties or themselves," he said. "One of them put his knife in part of a car roof to cut it and on the other side was a paramedic."
Mr Marritt is a watch commander in Humberside Fire And Rescue Service.
He also assesses firefighters in rescue challenges – competitions where teams see who can deal with a casualty most successfully.
And in the Romanian region of Brasov, he assessed firefighters in how they handled casualties trapped in simulated car crashes.
"Generally, the British are deemed to be the best in the world in terms of firefighting," Mr Marritt said.
Although he could not fault the Romanians' enthusiasm, their techniques were a long way behind what he was used to.
"They had very little concept of safe systems of working in their team approach and how to work together," he said.
"During the English challenges, I've had to tap people on the shoulder – but in Romania I had to shout and put myself as a barrier because of some of the things they were doing."
Mr Marritt said in terms of training, the firefighters were some way off Western rescue service standards.
"Their training systems are 30 years behind ours," he said.
But these old-fashioned methods were matched with cutting-edge equipment.
"The tools they were using were better than ours," he said. "The EU has quite heavily invested in the rescue capabilities in Romania. "They've had a lot of funding – unfortunately, they've got the equipment but not the training to use it."
There were 17 teams of firefighters taking part in the exercises. And the vast majority still have a long way to go.
"The casualty care was basic at best," Mr Marritt said. "Two teams were pretty good – one was a training school and one was from Bucharest."
Professional rescue teams work around the concept of the golden hour.
This should be the time between a crash happening and casualties arriving in hospital.
It gives firefighters about 20 minutes to cut people out of cars – and in England, if someone is not in immediate danger, crews take their time to avoid making the situation worse.
Almost all Romanian teams freed casualties quickly.
But, in Mr Marritt's opinion, they were too quick.
"If a casualty is stable, you take time to get them out," he said. "If they're not stable, you take shortcuts."
But the trainer believes the firemen do the best job they can.
Communist rule ended in Romania in 1989 and the fire service is still recovering from decades of neglect before that.
"Because Romania is a former Communist country, they're still in the development phase," he said. "They're an up-and-coming country and they've done a really good job of putting the infrastructure in place.
"Now they're going through the phase of putting the training in place."
The country's fire service, unlike the British one, is a military organisation.
Although Mr Marritt admired its discipline, he worried important questions were not being asked.
"The downside was that nobody would challenge the officers," he said. "Their commanders would always get involved in all the activities but they would not monitor safety.
"Their generals tell them they have to get hands-on and nobody questions them."
The fire service also suffers from a lack of training buildings.
"Their national training centre was an old Soviet building with gun towers round it," Mr Marritt said.
"Because the country is a developing country, they've got a long, long way to go. But the whole country is on the way up."
Romanian firefighters earn 300 euros a month – around £240.
"To be fair, there's money in the country but a lot of poverty as well," the trainer said. "They're not on a particularly good wage for Romania."
He has no illusions about how far the firefighters he trained still have to go.
But Mr Marritt feels his exercise has helped to set them on the right road.
"It was quite a humbling experience," he said. "I actually feel as though we've set the foundations that need to be built on. It's going to be a ten or 15-year programme."
But he hopes slow and steady will win the race.