Tele 162 (from 1929) in Jade Green, Chinese Red, Ivory & mottled Brown were made available when another plastic called Urea Formaldehyde was used instead of Bakelite.
http://www.britishtelephones.com/t200info.htm
The 2,000,000th instrument installed for HM King George V (1931) was made in a special finish and was modified in the 1980s at the request of HM Queen Elizabeth when Buckingham Palace replaced its PMBX with (aptly enough) a new Monarch call connect system, which also had to be modified because of the large number of manual extensions required and for these to immediately indicate to the operator which manual extension was calling.