Coal mining contractor

[Skaife]

Hi All
I’ve come across the description of a job (on a death certificate) of the  term ‘ coal miner contractor’ - this is around the time of WW1. I’m wondering if anyone can explain the term?
I’ve always assumed that miners were employed by the mining company who owned the  pit at which they worked. Now I’m wondering if ‘contractors’ gathered teams together and applied for work en masse.
Hoping someone on here can explain
Thanks for reading

[fiddlerslass]

From

1921

MINING AND QUARRYING OCCUPATIONS

contractor hewer ; bargain man, collier contractor, contractor collier, stallman
    undertakes hewing at fixed rate of so much a ton; may employ other men under him, whom he pays himself.

http://doot.spub.co.uk/code.php?value=042

[Skaife]

Thankyou Fiddlerlass -  I had searched on the internet but hadn’t found an explanation for the term. It now makes sense. I suppose it means in reality that there might be contractors undercutting each other to get the job. And of course a lot of the success rate would depend on where in the mine you were and how easy or difficult it was to extract.
Your explanation is much appreciated.