Window tax in London 1720s

[Sunlaws]

Hi
A family I am studying had a house in Marlborough Street in London, and a country house (!) at East Barnet in the early 1720s, and paid £1:10:0 annually for each property in window tax. Does anyone know how the tax was calculated at this time? I am trying to assess the size of the properties they are occupying.

Regards,
Lesley

[Kiltpin]

Hi Lesley, 

This gives a good insight -

https://en.wikipedia.org/wiki/Window_tax 

Regards 

Chas

[Sunlaws]

Thank you, Chas.

I had seen that, but was confused by it saying a top rate was introduced of 20 shillings for houses with 30 or more windows. It looks like that was in 1709, and I suppose it might have been increased to £1:10:0 by the 1720s, but it's hard to believe that the Marlborough Street house, at least, had 30 or more windows.
Regards,
Lesley