Studland Motor Road
The UK's first motorway is unclassified, tolled and links a small Dorset village to a chain ferry. Sounds rather improbable, I know, but I don't make claims like that lightly.
It wasn't until 1949 that the Special Roads Act provided the legal framework for motorways, and most history books will tell you that while the likes of Lord Beaulieu sought legal powers for motorways much earlier than that date, none were ever granted. But that's not quite true. In 1923 an act of Parliament was passed to enable the building of the UK's first road that was only for the use of motor vehicles. And so was formed...
With thanks to Jonathan Winkler for suggesting the Studland Motor Road as a topic that might reward further research. It certainly did!