Trying To Find The Song Title From network 3 Phone Ad

it is from the phone network 3 advert where the guy is sitting on top of an open topped double decker bus, and he grabs a balloon...the woman is in a bikini and sings...

"and now we're here..." then an addictive tune...

that's all i know to it...can anyone pleaze help me, im going crazy
ta xxx fran