Harry Potter star Matthew Lewis probably thought he had escaped the world of schoolboy teasing when he left behind character Neville Longbottom, but his Ripper Street co-star has admitted to “gently bullying” the show’s new addition.

Matthew Macfadyen confessed to the light-hearted torment as the cast discussed the fourth series of the 19th-century detective drama, which returns weekly on Amazon Prime from January 15.

Speaking of Lewis’s role as Desk Sergeant Samuel Drummond, Macfadyen said: “It’s always great to have fresh faces thrown into the mix and what a lovely fresh face Matthew Lewis has. Also you can bully them a little bit, that’s quite nice as well, isn’t it?

“Just gentle bullying,” he qualified.

Desk Sergeant Drummond, nicknamed Drum, is a “by the book” type, said Lewis, who soon learns that is not the way of H Division’s core cast of Detective Inspector Edmund Reid (Macfadyen), Detective Sergeant Bennet Drake (Jerome Flynn) and particularly, boozing surgeon Captain Homer Jackson (Adam Rothenberg).

Matthew Macfadyen, Jerome Flynn and Adam Rothenberg
Jackson, Reid and Drake return (Bernard Walsh/Tiger Aspect/BBC)

He said: “Drum takes Jackson for granted and thinks he’s just a drunk who is constantly causing mayhem. Then we have a wonderful scene that comes in the middle of the series where we’re in the lab and suddenly Drum realises there’s so much more depth to (Jackson) and (his) experience, and how much (Drum) still had to learn, not just police stuff, but just being a man.”

Adam said: “It’s a beautiful dynamic because it heralds in the new era. The Victorian age is coming to an end and I think that the three guys – me, Reid and Drake – are becoming dinosaurs and we’re seeing the people that are going to be taking over.”

But have no fear, the long-timers still lead the action in a series Macfadyen described as “gruesome, bigger and filmic”.

Series four opens with brothel madam Long Susan (MyAnna Buring) locked up in prison for the murder of 55 people and seeking a way to avoid the noose, while a restless DI Reid – reunited with his daughter and recovering by the sea after being shot by Susan – is called back to Whitechapel to save his friend Isaac Bloom (Justin Avoth).

Reid’s return, Macfadyen said, will be “uncomfortable to watch”.

“There will be lots of clashes. There is a slightly weird thing when Reid comes back to Whitechapel and then there’s an odd dynamic with Reid and Drake, because Drake is now the head of Leman Street (Station).

“There is an odd status thing with those two which is kind of uncomfortable to watch.”

Meanwhile Jackson is dealing with “a very heartbreaking and urgent agenda” to save Long Susan, said Adam.

Asked if Long Susan’s bid for freedom works, MyAnna teased: “I can’t say. What I can say is that the noose is waiting. It’s swinging for her.”

As well as Lucy Cohu and Derek Riddell returning as ”another treat and nod for audiences who have been with us since the beginning”, David Threlfall will star as villain Abel Croker.

“He was wonderful. He makes everyone around him feel great and not only that but he is a brilliant actor,” said MyAnna.

This will be the first series made exclusively for Amazon Prime video after the online giant stepped in to save it when fans protested at the BBC decision to cull it after two series.

The freedom and financing has made this series “like a film, there is a feature length episode, and the production quality is second to none”, said Lewis.

The plot line too will lead to a gripping climax.

“It’s all good but the overarching story as it comes to a close in the last three hours is just going to fly by. I’m looking forward to seeing it myself,” he added.