Some years ago now, I came across Census data from 1841, for a Surrey village, which initially had me puzzled. There were many miners suddenly employed in the area. It happens, as it quickly turned out, that the census coincided with the construction of a railway tunnel on the London-Dover route. Now I am wondering whether navvying in general took its toll on mining employment. Was there competition - was railway construction more lucrative for miners than digging for lead, or tin? Are there mine records decrying the loss of workforce to railway navvying?