Re Thomas Cox's house, I recognise it, it use to be on the right hand side on Longton road going towards longton. (now demolished). There is now a large roundabout in its place used to enter the Garden centre and entrance to Trentham gardens. It was opposite what use to be Ash Green Post office.
Now Trentham Park railway line, no to my knowledge there were no railway lines either over the bridge or in the tunnel, as the building of this line from Trentham Park station was abandoned when WW11 broke out. When I speak about Trentham Park railway station I am talking about the station which use to be opposite the what is now Clayton lane (Dog Kennel Lane) on Boma Road A34, (Ex London Road). Don't forget all metal was removed for war purposes including the railings which use to surround our estate house(Yellow Houses ) on entering the park. This also included the gates to the Park as my granddad was very upset over this.
The branch line started from what is now Trentham station and went to Trentham Park station and was intended to go to pool Dam in Newcastle to link up with the Newcastle - Market Drayton line.
An ironic aspect of this, is that this branch line to Trentham Park became busier than ever when the London clearing Banks evacuated to Trentham Gardens ballroom in 1939. Indeed one of the reasons for this site being chosen was because it was capable of being fully serviced by postal and railway authorities. I hope this is of help.