It's the bus advert for milk featuring Jade Jones, Laura Trott and Nicola Adams. It has the slogan 'm' powered, featuring them in their sports gear looking badass:
www.metro.co.uk/lifestyle/912385-team-gb-girls-sport-milk-moustaches-for-latest-make-mine-milk-campaign
Very glad it shows them as they are and didn't feel the need to make them look uber-glamourous or other such nonsense.