While the original test card girl was a static image, Myleene will step out of the frame and offer a 10-minute tutorial to Sky customers on understanding high definition TV.

The cards were created in the 1930s to help engineers fine-tune TV sets.

The most famous - Test Card F - first appeared on our screens 40 years ago. Its star was Carole Hersee, eight-year-old daughter of BBC engineer George Hersee.

Test Card F was the first to be in colour and it featured a person so that adjustments could be made for skin tone.

She was pictured playing noughts and crosses with a grinning toy clown. The choice of game was not random - the ’X’ marked the centre of the card.

Test Card F was first shown on BBC Two in the summer of 1967 and by the time regular transmissions were discontinued in May 1983, it had been shown for an estimated 70,000 hours.

Carole is said to hold the record for the most TV appearances.

The image has such a hold on the public’s imagination that there are web sites set up in its honour.

Myleene to have a girl? - May 21 2007
Myleene Klass has apparently lifted the lid on her pregnancy - reportedly saying that she’s expecting a little girl.

The 29-year-old - who is now five months pregnant - also revealed that her hormones are all over the place, reports the Daily Mirror.

"I’m thinking about names but I’m so hormonal, I keep going, ’Let’s call her Mango, that’s brilliant’," she’s quoted as saying.

"We’ve been talking to the baby and saying, ’Do you like such and such?’, and she will kick if she hates it. Some names have gone right out the window."

The pretty brunette is working throughout her pregnancy, including her job interviewing celebrities on the Screening Room for CNN.

"Robert De Niro gave the baby a rub," she grinned. "I also interviewed Johnny Depp. It’s funny now I’m pregnant my opinions have completely changed. Before I wanted him to have my babies, now I’m like, ’Oh, he’s a dad, isn’t he?’, and I want to know about his babies."

Myleene’s baby worries - April 18 2007
Pregnant Myleene Klass is reportedly worried that she is going to have an enormous baby.

The star, who is four months pregnant, is concerned after realising she had ballooned three dress sizes in just a few weeks - and she thinks the baby may follow in the footsteps of her Irish fiance Graham Quinn.

"I’m definitely in trouble," she told Closer magazine. "Gray was a big baby, so it’s obviously getting its size from him.

"People can’t believe I am showing so soon. We’ve had a history of small babies in our family but this one’s huge already."

The 29-year-old says she’s been having non-stop cravings. "I’m having major cravings," she said. "I’m eating loads of cookies and chips.

"I haven’t felt the baby kick yet, but I’ve been feeling very nauseous and had one episode of morning sickness in front of a police van which wasn’t my most glamorous moment."

Myleene, who has just started modelling for Marks And Spencer, added: "It’s like the ultimate present - I’m so happy about it."

Pregnant Myleene shows off bump - April 6 2007
A smiling Myleene Klass showed off her bump during a photoshoot.

The 28-year-old musician and TV personality posed in a red chiffon dress to publicise the new Marks & Spencer campaign.

She is expecting her first child with fiance Graham Quinn who was a bodyguard for the band Hear’Say in which she shot to fame.