Keelie Roberts, 22, left her 73-year-old grandma in a shock when she had a fling with her other half.

Keelie now plans walk down the aisle with the 63-year-old fella.

The affair began when Margaret Linden and Jack Dobson asked the jobless girl to stay with them.

But when Margaret came home she was stunned to see her topless granddaughter romping with Jack on the sofa.

However, Keelie has defended her act.

"Jack's better off with someone wild like me. We have a good, healthy sex life," the News of the World quoted her, as saying.

She went on: "He's far more experienced than boys my own age.

"I feel sorry for gran but you can't help who you fall in love with."

After Margaret threw them out, the odd couple now live in a flat in Camden, north London.

The unemployed Keelie said: "I did think about working as a hairdresser but I can't be bothered. If I want money for new clothes or to go out, I just ask Jack.

"He's just bought me a 3,000-pound engagement ring and gives me about 300 pounds a month to spend on myself, plus he pays the rent on our flat and all the bills.

"Obviously he'll die before me but he'll leave me financially secure. He's written me into his will so I don't have any money worrries."

Keelie revealed how the former English teacher Jack made his first move during ITV drama Heartbeat while Margaret was not at home.

She said: "I was shocked.

"He's no Brad Pitt but it doesn't bother me that he's old and wrinkly. And I love seeing people's faces when they learn we're lovers!"

And Jack was never happier.

He said: "I did think about how Margaret would feel but I just wanted to be with Keelie."

Margaret has now disowned the pair.

She said: "Keelie's ruined my life.

"I let her into my home and she repaid me by stealing Jack. It's disgusting." (ANI)