Window tax

When walking around London you occasionally see bricked up windows, particularly on older buildings. This is due to a tax on the number of windows a building had, introduced by William III in 1696:

Window tax was relatively unintrusive and easy to assess. Certain rooms, particularly dairies, cheeserooms and milkhouses were exempt providing they were clearly labelled, and it is not uncommon to find the name of such rooms carved on the lintel. The bigger the house, the more windows it was likely to have, and the more tax the occupants would pay.

I was told this is where the phrase daylight robbery comes from but the evidence seems to be inconclusive!

/thx @jethro247