Roman brickworks ...

Thanks to David Meadows' Explorator, I found this link to some Roman brickworks near, well, Rome:

Discovery Channel

It's also mentioned at:

The Scotsman

and latterly

The Daily Telegraph

There aren't many civilian tile stamps in Britain; most are army. The ones local to York are the 9th Legion Hispana (up to the early 2nd century and the 6th Legion Pia Fidelis (from the early 2nd century to, presumably, the early 5th century).