Great photo of a old and weather-worn Tube Map, taken at White City tube station. If you look closely, you can see that more than one layer of map is visible in certain sections, giving sort of an archaeological cross-section of different eras (See the doubled-up interchange station symbols at Euston for a good example). The most visible map seems to date from the early 1970s as it shows the Highbury branch of the Northern Line towards the upper right of the photo, soon to be transferred to British Rail.

Source: jayay/Flickr