Complete colour blindness is rare. Colour deficiencies such as the inability to distinguish shades or sectors is rather more common, in South Wales between 10% and 20% of the adult male population.

The defective gene is carried by the female of the species, but only effects the male.

Thats why in my family we were able to trace the source back to the Pugh family of Bedlinog and Aberfan (my maternal grandmother) Both my grandfathers passed colour vision tests, on one side as an apprentice in the merchant navy, and on the other, a railway signalman.

Gareth