The creative uses eyeblasters, which float across a web page, depicting clouds and the Virgin Money Credit Card with angel wings and a halo. Users click on the image to receive more information or sign up for the card.
The eyeblasters were developed by Glue London, an agency in which St Luke's owns around a 25 per cent stake.
The campaign, which was planned and bought by Manning Gottlieb OMD, is running across websites including Virgin.Net, Times Online, Telegraph.co.uk, Moneyextra, Channel4.com and dotmusic.
Amy Lennox, an account director at Manning Gottlieb OMD, said: "We needed to make a splash, so a large format creative was used, and we are testing to see if it can drive conversions when the consumer is browsing in a totally unrelated environment."