One of our supporters has pointed out that the mini-roundabout at Church Corner is the oldest true mini-roundabout in the UK and probably the world.
The concept of a mini-roundabout was developed by the late Frank Blackmore (1, 2, 3) a Traffic Engineer who worked for the Road Research Laboratory. He first developed a roundabout that could be used in restricted urban areas resulting in the development of a roundabout with a 2 to 4 metre wide central island. This was first installed in Peterborough in October 1968 near London Road and Oundle Road, but was replaced by traffic lights in 2008.
However Frank then went on to develop a small roundabout which had no central island and was just a painted white circle. This was the first over-runable or fully traversable by cars roundabout and was defined as a mini-roundabout by the government in 1975. As the first of this design was installed in Benfleet in May 1970 it makes it the first in the UK and the world and is still in operation today.
Fortunately CPDC have given us access to some photographs taken at the time showing the roundabout being installed and the first few cars that traversed it. Some further details are here. The Benfleet Urban District Council then followed up with photos on the 11th June 1970.