Guy Henry reveals why the normally hard-nosed Holby boss is prepared to overlook Oliver’s cheating next Tuesday on BBC One…

In a special episode that flashes back nine weeks, Oliver returns to work after sister Penny’s death and goes off the rails. What happens?
“Oliver is still reeling from the loss of his sister and the guilt that he passed her doctor’s exams off as his own, which no one knows about. He returns to work, but makes a lot of mistakes. When he hits rock bottom, Oliver decides he wants to confess everything to Hanssen and resign from Holby.”

Oliver writes a letter admitting that he’s not really a qualified doctor. How does Hanssen react?
“He puts the letter in his drawer, knowing that Oliver will come and see him for his assessment. When Oliver finally comes to his office, Hanssen gives him some fatherly advice, telling him about his own failures as a child when his dad died. Then, when Oliver asks what he plans to do about the letter, Hanssen replies: ‘What letter?’”

Why is Hanssen turning a blind eye?
“Because he hears about Oliver saving a patient’s life under difficult circumstances and doesn’t think a good doctor should lose his chance at a career in medicine.”

So viewers will see a different side to Hanssen?
“Definitely. Hanssen is always seen as a baddie – he’s sarcastic, rude and difficult. But if he thinks someone does a good job, he tries to encourage them. You realise that Hanssen is not just a penpusher trying to make cuts at the hospital, he does really care about his team. It was nice to reveal a more human side to Hanssen.”

Elsewhere, can viewers expect to see love blossom between Hanssen and Sahira, played by Laila Rouass?
“He is attracted to her but, first and foremost, he thinks she’s a wonderful doctor and a bloody good surgeon – and he doesn’t want to distract her. So there’s more unrequited love to come!”

You’ve been in Holby since last October. What have you most enjoyed about being on the show?
“I love playing the slightly strange Hanssen, but I almost considered walking out after my first six weeks because the days can be very long. The cast and crew are such a lovely lot, though, which makes the job worthwhile.”