I've been looking into the history of the Brandlings of Gosforth, one of the families of the 'Grand Allies', who were basically a cartel of wealthy families or families who were dubbed 'wealthy commoners' of coal mines in Northeast England in the 17th to 18th century. I'm having trouble finding more information about these families. I'm surprised and curious as to why there isn't more information about them, both on genealogy as well as what mines or collieries they owned. Is it simply because they weren't necessarily nobles or was it because the information was lost or so minuscule that it didn't matter? Here's the information I have found so far: http://englandsnortheast.co.uk/CoalMiningandRailways.html https://en.wikipedia.org/wiki/Brandling_of_Newcastle
You'll find more in local archives. (Staff may be willing to find a handful of things via email request, but beyond a certain amount you'd need to pay them and/or employ a researcher.)
An old page from the Tyne & Wear archives - takes a while to load - mentions a holding called 'The Rise and Fall of the Brandlings'.
Newcastle archives, and possibly Newcastle Lit & Phil and the smaller County Durham record office may have material about them
Local history societies may have small publications or knowledgeable members, but the web presence is patchy:
Durham Local History Society has an active website, but a current umbrella site for Tyneside and Northumberland appears to be lacking with just this old page, although some small very local societies have sites:
http://www.sunnisidelocalhistorysociety.co.uk/gateshead.html
http://www.thefelling.com
The Durham Mining Museum may be more focused on the mine workers but may have helpful pointers.
Beamish is a huge museum, again with a focus on every day life for working class people, but its size can mean it gets knowledgeable staff.
The Brandlings get a few mentions in John Nef's Rise of the British Coal Industry Vol II - you can find it on Google books.
This paper (Edward Walsh and Ann Forster, 'The Recusancy of the Brandlings', British Catholic History, Volume 10, Issue 1 January 1969 , pp. 35-64) on their relationship with Catholicism may be of interest depending what you're researching.
I also turned up this page related to Middleton Park in Leeds, whose friends group has evidently done some archive work on a branch of that family.