CORONATION Street fans were stunned upon realising a star’s real-life partner made a top secret cameo this week.

Viewers watched on as Cassie Plummer (Claire Sweeney) was arrested in the ITV soap.

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It came as Ken Barlow (William Roache) at last discovered how Cassie had been drugging and manipulating him.

However, viewers were shocked to learn who played the officer arresting Cassie.

It was none other than Matthew Martin – who is the real-life partner to Rob Mallard aka Daniel Osbourne.

A Corrie fan wrote: “Love that Rob Mallard’s partner arrested Cassie last night.”

Meanwhile, Matthew took to Instagram where he shared snaps in costume – including one with Rob.

He captioned: “Ey mam! I’m on the telly box!

“Quite a surreal time being pulled in SUPER last minute to step in as a Policeman to arrest Cassie Plummer/@claire.sweeney.

“All thanks to @mossy737 for giving me the opportunity to work on the iconic show that is @coronationstreet.”

Addressing his partner, Matthew wrote: “And of course my lad @rob.mallard for being the biggest support and showing me the ropes.”

Cait Fitton, who stars as Lauren Bolton, commented: “There he is”, while tagging Matthew.

Coronation Street’s Ken Barlow in serious danger as Cassie Plummer’s sick scheme takes a dark twist

Former Corrie star Emrhys Cooper, who played Rowan Cunliffe, simply left love heart and applause emojis.

Viewers were stunned last year when Cassie began poisoning Ken – having begun caring for him after an injury.

Ken later let Cassie go owing to financial constraints, but she started drugging the soap veteran to keep him reliant on her.

She continued this despite suspicion from Ken’s stepdaughter Tracy (Kate Ford) and other residents.

Furthermore, Cassie even stole his credit card to fund extravagant purchases.

But on February 26, everything came to light and Ken forced her to leave.

A further dramatic twist saw beloved Ken suffer a terrifying heart attack.

He was rushed to hospital, where he disclosed what Cassie had done to his family.

Cassie attempted to flee the cobbles, but was ultimately arrested amid the chaos.