When were targets introduced in the valleys?
Generally I've not seen them on pre 1950 photos, but I've searched through my photo collection and found the following early photos:
GWR loco 197 target C42 photo date 1923
GWR loco 706 triangular target 6 - Cathays 1926
GWR loco 44 and an ex Barry B1 with target Y29 at Radyr ca 1930
GWR loco 56 with diamond target CD7
GWR loco 68 with triangular C21 ca 1934
GWR loco 631 with diamond target CD8 at Cardiff dock in 1924
RR loco 30 with square target C34 & mixed goods train at Heath in 1919
RR loco 69 with square target C29 & passenger train ca 1914
RR loco 78 with square target SP10 & mixed goods train ca 1920
RR loco 88 with square target C14 shunting a mixed goods train at a station
So I conclude that the Rhymney railway used targets. Which other companies used them and when were they introduced?