The 79 year old will show off her fancy footwork in the Christmas Day (25Dec12) special, and Hancock admits she relished the opportunity to learn a new skill - even though it was tougher than she expected.
She tells Britain's The Sun newspaper, "It's far more difficult than I thought. But I am really enjoying it. I have never wanted to do a series because it would take too much time but it's nice to do this Christmas special.
"At my age, it is marvellous to learn a new skill. Ballroom dancing is a wonderful exercise for older people and as long as I don't fall on my bottom and let everyone down, I will be alright!"