Pete,
May be duplicating myself a bit, but perhaps this might tidy up this particular thread. Went to Hathersage this week and got hold of/bought as much of the local literature re the COCKER's that I could. Broom Cottage I found thanks to your precise directions; and I also discovered Rock House (opposite the pub The Scotsman Pack) and Moorseats, up above the village - both places being at one time lived in by this family.
I'm wondering whether the "Park House" I was enquiring about might have been a mistranscription for "Rock House". Moorseats was an extra bonus, a lovely mansion, and I suppose an indication of how well they did out of the needle producing (terrible conditions for the people they employed, though, I'm ashamed to say)
keith