Moorgate Station is being stripped and retiled, and for the most part the walls are strangely bare - with an intriguing exception. By the ticket barriers for the Stevenage trains, among the tiles and signs, a painted advertisement from the past peeks out.
We can make out some words: 'The National Building Society', and a hint of 'founded' at the bottom. It's apt: the National Building Society was based in Moorgate. It had been founded in 1849, as the National Freehold Land and Building Society, by three Liberal MPs; by 1944, when it merged with Abbey Road to form the Abbey National, it was the sixth largest British building society.
Mutual building societies, owned by their members, began in the late eighteenth century; they boomed in the nineteenth and twentieth centuries, but legislative changes saw most of them become limited companies in the 1990s. The first building society to demutualise, the Abbey National became a bank in 1989. Now, the Abbey National is also gone, submerged into Santander. And this little bit of history may soon go, too - but for the moment, it offers a glimpse of this important strand of our financial past.