Crystal Yu, who plays Casualty’s no-nonsense medic Lily Chao, reveals her behind-the-scenes hysteria when Gary Lucy guest starred in a special stand-alone episode of the long-running medical drama.

Gary Lucy, best known for his roles on Hollyoaks, EastEnders, The Bill and Footballers’ Wives, stars in Casualty as smooth-talking, shifty patient Valentine Kildare, in a spooky one-off special.

On screen Lily fails to be charmed by Valentine, but off screen Crystal reveals she was star struck by the former Hollyoaks heartthrob.

“Lily contains her composure and professionalism, but Amanda Henderson (nurse Robyn) and I were very giggly during our scenes with the Gary! He’s a wonderful actor and it was a lot of fun to film,” Crystal told What’s on TV.

“There were a lot of behind-the-scenes hysteria on the night shoots for this special standalone episode because we were all so tired!”

The episode is something of a Holby-whodunit, with Lily channelling Miss Maple on this especially spooky night shift, when she begins to suspect Valentine is killing off her patients!

Crystal explained to What’s on TV: “It’s Casualty in the Dark’ – Casualty on a spooky night, where murders are taking place!

“The electricity keeps breaking and everything seems to be going wrong. So Lily puts on her detective hat, as she wants to know the truth.”

Crystal, who joined Casualty as junior doctor Lily in 2013, teased: “As usual, Lily tries very hard to find the truth but some things don’t work out! Lily thinks Valentine is dodgy and doesn’t trust him – the episode has a great twist!”

Speaking about his first ever Casualty appearance Gary said: “I’m so pleased to be part of this fantastic stand-alone episode of Casualty. It’s a well-written and directed piece with a strong set of regular characters. I had huge fun playing a different character in the longest running hospital drama. Tune in to watch the mystery unfold!”

Catch Gary and Crystal in action on Casualty on Saturday, November 15 on BBC1 at 9.15pm.