Doulton insulators goes back to 1840s and only closed in 1999.

Apr 4, 1850 - I find, on reference to my office papers, that this insulator was introduced upon the Red Hill and Reading Branch, the first line of telegraphs which the South Eastern Railway Company themselves erected. The first order for this pattern was given on April 4, 1850, to Doulton, of Lambeth, to be made in his brown stone earthenware.

Lee Southern