He revealed to ITV Press Centre: “As part of my research I witnessed four brain operations. From my time spent on hospital wards and in surgery I was able to understand and appreciate the day-to-day life of a neurosurgeon.”

Written and created by Peter Bowker (Occupation, Desperate Romantics), the six-part series also stars Sarah Parish (Doctor Who: ‘The Runaway Bride’) and Tom Riley (Bouquet Of Barbed Wire).

Nesbitt continued: “I’ve seen how neurosurgeons drill through the skull, pull back the skin on the head and make an incision into the brain. I’ve seen the brain, which is an amazing organ, pulsing away. I’ve seen the revelation of an angry, horrible, grey-black tumour, which has then been removed. It’s incredible to know that the brain can survive some of the procedures that surgeons perform.”

He added: “Thankfully I’m not squeamish, but I was incredibly nervous and very fascinated… It was the hardest but the best twelve weeks I’ve ever had.”