Wigan Album

I have recently obtained a large collection of black and white photographs showing people and underground scenes from Parsonage Colliery. Which I will be putting on the site over the next few months. This one shows miners with their N.C.B. Certificates Can anyone say what they were for and name any of the people I don't know the date but could be anything from 1960's-1980's.
The photographs were issued by the PUBLIC RELATIONS DEPT. N.C.B. Anderton House Lowton