He may be appearing nightly on screens across the UK, but Maidstone’s Callum Knell’s admittance into the Big Brother house came as a shock to his friends at home.

As 4.32 million people tuned in for the launch show, the 28-year-old reality star’s loved ones were anxiously waiting for their guarded secret to be revealed.

Friend Marc Horton said: “I had no idea he was going in there. I was only with him the other weekend and he didn’t let on at all.”

The former Maidstone Grammar School pupil and football coach is the eldest of six children, including Jake, 27, Karis, 25, Tayla, 23, Raegan, 16, and nine-year-old Elijah.

Callum’s mum, Lin, was glued to the TV in their Plains Avenue home when the hit show premiered on Thursday.

She said: “I was screaming when it was his turn to go in. After that, the phone and Facebook went mad... It’s been really surreal.

“Callum has talked about going on Big Brother for years and now he’s on it. It’s a once-in-a-lifetime opportunity.”

People might recognise the budding television personality as manager of the under-nine Bearsted Rangers or from when he was a lifeguard at Maidstone Leisure Centre.

The keen sportsman, who plays for the 3 Suttons Football Club, saved 19 lives at the pool and a further nine outside of work.

His days cooped up in the Channel 5 reality house are a far cry from last year, when he enjoyed the wide open spaces of the USA, as a sports coach.

Sister Tayla said: “Callum is very active. He loves sport and really has a passion for teaching.

“It’s a shame he’s being portrayed as boring in the house as he’s anything but. He’s confident, intelligent, witty and very loud.

“We think he’s spending the first week sussing people out and then he’ll come out of his shell.”

Callum’s siblings think a “bromance” could be on the cards with housemate Sam and have noticed chemistry between their brother, who is a self-confessed ladies’ man, and Charlie.

Callum fans have at least a week more of seeing him in the house after he escaped nominations.

Big Brother airs tonight (Friday) at 9pm.