So, I stumbled over this while researching my wife's great grandfather William Thomas (b. ~1841). In the 1861 census he, along with three other men, is shown as a lodger in a house in Heston with occupation given as "Labourer in Brickfields". I have tried to attach an image snipped from the page but, in case that doesn't work, the full entry for that household is as follows:
NAME / POSITION / MARITAL STATUS / AGE / OCCUPATION / PLACE OF BIRTH
William Taylor / Head / Married / 64 / Shopkeeper / Hayes, Middlesex
Ann Taylor / Wife / Married / 66 / - / Lampton, Middlesex
John Becket / Lodger / Unmarried / 41 / Labourer in Brickfields / Not known
Wm Thomas / Lodger / Unmarried / 19 / Labourer in Brickfields / Isleworth, Middlesex
James Dix / Lodger / Unmarried / 68 / Labourer in Brickfields / Heston, Middlesex
Charles Robinson / Lodger / Unmarried / 18 / Labourer in Brickfields / Heston, Middlesex
I realise this doesn't give much insight into the actual brick works but it may be of interest, nevertheless.
If there's anything more I can do then feel free to ask.
Kind regards
Dick Francis