When the shambling Mr Harvey (Timothy Spall) steps on the coach at the start of a chaotic school trip to Salisbury Cathedral, he little expects that by the end of the day, he will have opened up to his colleagues and pupils about events which have had a profound effect on his life.
In doing so, he finds a way to put the past behind him and renew his connection with the present.
"It's a fantastic story," says Timothy Spall. "It's about a man shedding his unhappiness by finally coming to terms with the reasons for it. Like a lot of people who've experienced a tragedy, he's trapped and has almost built his personality around his misery and his secret.
It's about a man shedding his unhappiness by finally coming to terms with the reasons for it.
Timothy Spall"In a witty way it is a redemption story. Through allowing himself to connect as a human being with the kids he's been teaching all his life, he finds an escape.
"In the end it's the two most incongruous characters - Mr Harvey and Helen (Natalie Press) – who help each other.
"It's also an exploration of a faithless society. These kids don't have any religion but that doesn't mean they don't have the potential for kindness and spirituality. It's about getting in touch with something that doesn't have a price tag on it."
In the drama, the kids suddenly see Mr Harvey as a person outside the classroom, something which Timothy can relate to.
"As you get older you look back and think how old teachers seemed to you. I was lucky as there were a few teachers at my school who were kind enough to take me on as a person. My drama teacher, in particular, encouraged me to become an actor. She told me what to do and I did it."
"It's a colourful, energetic film," adds executive producer Laura Mackie, "at its heart is a life-affirming story about people's need for something bigger in their lives.
"It's the kind of school trip from hell we've all been on, with a few jaded teachers trying to shepherd bored kids around some site of cultural significance they couldn't care less about. But for a few, the day out has life-changing results."
Mr Harvey Lights a Candle is the first television piece from award-winning author Rhidian Brook. It was filmed on location at Salisbury Cathedral and various locations around London.