The actor became a hit with viewers and was one of the show’s first LGBT+ characters.
His first-ever screen debut was in the video for the Chemical Brothers’ 1995 single Life Is Sweet.
The following year he landed his big break as bleach-blond-haired Sam, who became one of the show’s likable characters.
Jonathan’s character’s sexuality played a focus point for many of his storylines – including one where he found out a female car crash victim was having an affair with his boyfriend.
After four seasons on Casualty, he was written out in 1999 and swapped A&E for rural Yorkshire.
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As well as playing PC Steve Traynor, he composed the show’s theme tune.
His character had an affair with Helen Trent, who he went on to marry.
However, his on-screen love was killed in an explosion, leaving him heartbroken.
In 2007 Jonathan quit the show and was replaced by Joe McFadden.
He featured in US crime drama NCIS and BBC drama The Club and even scored himself a film, starring alongside Naomi Watts in The Somnambulists.
Jonathan is married to Shelley Conn, who starred as Lady Mary Sharma in Netflix’s Bridgerton, and they had a son together.
They also both star together in Death in Paradise as Xander and Marina Shepherd.
Long gone is his short blonde hair and it has been replaced by dark brown waves.
His most recent TV work is Irvine Welsh’s Crime where he stars as Mark McKendrick alongside Dougray Scott and Angela Griffin.