Thank you, Kushi. I am just your humble administrator, but I have fantastic friends all over the globe who help me.
Maybe you'll find the index handy. It needs more work, which I shall do in due time, but, together with the pictures, I think it allows further research.
For one thing, there is a pattern evolving where the late d-tokens were put together with generic reverses and what may have been a city seal. This means, that a patient type can sort out those generic reverses and maybe connect them to a token producer and maybe even a time period. Another point is the diameter, sometimes clearly non-decimal (22 mm = 7/8 inch and 25 mm = 1 inch), sometimes decimal (e.g. 20 mm). My guess is that they point at different machinery, made in Britain or elsewhere.
Mapping the places of issue might be useful as well. My working hypothesis is that you'll most often find them in big cities, industrial and mining centres and small ports: all having pockets of deep poverty. That again makes it strange that there are few or no bus tokens from Scotland (except Edinburgh and Glasgow), Northern Ireland (except Belfast) and Wales.
Another area that needs more work is the colours. It's relatively hard to read these tokens, especially in lamp light. They must have been difficult to check. Yet, there are surprising numbers of fixed colour/size/denomination combinations, such as 1 d, 22 mm, red. It looks like an open invitation to cheat…
I am hoping that one day someone will be inspired by this thread to dig into such issues and come up with answers and numbers.
Peter