Passers-by may have been pleasantly surprised as they ran into a horde of svelte swimsuit-clad women atop London's Millenium Bridge on Monday.

Marking the 50th anniversary of Special K, 100 ladies joined sports presenter Kirsty Gallacher to show off their enviable figures as a result of following the cereal's regime.

"Kirsty was perfect to front the birthday launch as nothing captures better the classic Special K girl than a curvaceous naturally beautiful brunette," said a spokesperson for the brand.

And no wonder the pretty presenter was full of smiles as she posed on the London landmark.

The mum-of-one became engaged to long-term partner, rugby ace Paul Sampson, last week.

The couple have been together for eight years and have a two-year-old son, Oscar.