hehe, it's probably a number of different bras. There's something by Gossard I think that is specially made to give smooth lines. I can't remember the name but they had them in Debenhams today so check out there.
there are loads of them around, i am currently wearing one from Next, it is completley seamless and only �12.99, also i have a couple from marks and sparks that were around �16 quid, cheaper than gossard and just as good!