Kimberley Walsh had a ''working relationship'' with Nadine Coyle and Sarah Harding.

The 31- year-old singer - who was part of the chart-topping girl band with Nadine, Cheryl Cole, Sarah and Nicola Roberts - admits she never managed to find a solid friendship with the Irish beauty and the blonde star because they just didn't click.

Speaking to HELLO! magazine, she said: ''With Cheryl and Nicola I found a friendship that got deeper and deeper as the years went by, whereas with Nadine and Sarah it was more of a working relationship. I didn't see the point in writing a book [her new autobiography 'A Whole Lot of History'] if I was going to skirt over things and not be honest.

''I'm not saying I didn't get on with them, but Sarah and I are polar opposites, so we were never going to be best buddies. That doesn't mean I don't care for her or have lover for her or wish her the best.

''As for Nadine, in the early days I took her under my wing because she'd never even lived away from home before. My instinct was to look after her and we were really close. But she was 16, I was 21, and you change. As we matured into young women, I just began to relate to her less and less.''