Hi, Just seen this post and for what it is worth would like to offer my opinion.
Hi,
Harraton Colliery was situated in the village of Harraton, in the district of Chester-le-Street Town, Co. Durham, part of that pit was called Nova Scotia, and became known locally as 'Cotia'
Cosha, Coshaw or however they felt like spelling it. Could this be the solution to your problem? Our grandfather was a miner here for many years. Hope this might help.
Regards,
Dorothy