Cast Iron Railings at St Paul's Cathedral

This evening I went for a walk with the Constructors - "City Gardens". It was great fun and I learnt a lot. One new bit of info was that the railings around St Paul's are one of the earliest uses of cast iron (1710 - 1714).  Christopher Wren, apparently didn't want a fence around the Cathedral at all, and said that if there had to be one it should be of wrought rather than cast iron. However wrought iron was deemed too expensive and so these cast iron ones were commissioned. They were made at Gloucester Furnace, Lamberhurst, in the Weald of Kent and surrounded the cathedral, including seven gates. They weighed two hundred tons and cost six pence a pound. The total cost was £11,202 – a lot of money in 1714! We were told that the railings on their own are Grade 1 listed!