Hi Liverpool Lass,
Thanks for the reply. Yes, I've tried Staffs R.O. at Stafford (visited) & Hanley (phoned), I've also emailed Trentham Gardens to see if they have any old plans of the estate - they don't.
Stafford had plenty of info on the Estate but I couldn't locate anything specific to the Gas Works or Gas Manager/Makers House. I did get a link to Dunrobin where the Gas Maker (Elijah Derbyshire) had moved in his employment with the Sutherland family in 1871 along with his wife & two youngest daughters.
The record took the form of complaints from the Steward as to how much coal was being used to produce gas for the Castle, although eventually there was an admission that the coal in that part of Scotland was different to the type used in Staffordshire and that Elijah - who by this time was 60 - wasn't slacking by not cleaning out the Retorts properly

Will just have to keep searching I think - and it's not even my side of the family!!