Great Britain Early Postmark Identification Resource.
During my efforts to identify my stamps properly, I came across this Stanley Gibbons publication from 1909. Apparently, it was donated to Cornell University and is copyright free.
It describes the development of early postmarks in the UK and in the appendices, towards the end of the book, there is what seems to be a complete list of the obliteration mark numbers and their towns. For example, I now know that my Scott #34 4d Vermillion stamp bearing the postmark number 447, was posted in Leeds, Yorkshire.
Anyway, I hope GB stamp collectors and sellers may find this useful.
https://www.gbps.org.uk/information/downloads/postal-markings/The History of the Postmarks of the British Isles from 1840 to 1876 - John Hendy (1909).pdf

It describes the development of early postmarks in the UK and in the appendices, towards the end of the book, there is what seems to be a complete list of the obliteration mark numbers and their towns. For example, I now know that my Scott #34 4d Vermillion stamp bearing the postmark number 447, was posted in Leeds, Yorkshire.
Anyway, I hope GB stamp collectors and sellers may find this useful.
https://www.gbps.org.uk/information/downloads/postal-markings/The History of the Postmarks of the British Isles from 1840 to 1876 - John Hendy (1909).pdf

Comments
Note that your link has the last few letters/numbers not hot so anyone interested should copy & paste the entire thing into their browser (clicking as is will bring one to a 'page not found').
Thanks for noting the problem.
Unfortunately, it copies into the forum like that and I have no idea how to change it. I've run it through a URL shortener Try this link: https://bit.ly/3jN058R
I works for me.
The site is in French and it seems to have a large collection of postmarks with details of their usage.