Britain's Prince Harry has been giving Cressida Bonas karate lessons.

The handsome royal wants to ensure his girlfriend is able to defend herself if attacked and has been teaching her moves he learned as a teenager.

A source told the Daily Star newspaper: "Harry wants Cressida to be able to look after herself, so he has been giving her karate martial arts training.

"He wants her to be able to fight back should she ever be in any immediate danger."

Harry - who is set to attend the London Marathon on Sunday (21.04.13), the day of his grandmother Queen Elizabeth's birthday - is also said to act like Cressida's "personal bodyguard", constantly protecting the 24-year-old beauty.

The source added: "He thinks that by helping Cressida learn these moves, she will feel more confident out and about without him. He is a bit like her own personal bodyguard when they are together but when she's alone, he worries."

The couple made their first public display of affection during a skiing trip in Switzerland earlier this year and have even been given nicknames by their close pals.

The insider said: "Their mates have started nicknaming them Barbie and Ken."

While the prince is reportedly smitten with Cressida, the pretty socialite is still unsure of her future with him and needs time to consider her options.

A source recently said: "Harry is quite open about his strong feelings. Cressida, I think, still needs to be convinced.

"She loves spending time with Harry, but she is not sure if she can commit to him long term."