Here's an excerpt from the obit:
He then worked on the idea of a roundabout with no central island in his own time, knowing it would not be taken seriously. But, after a long struggle, he finally got the first mini-roundabout introduced in Peterborough in 1969, stationing himself there with a loud-hailer to tell motorists what to do when they met it.
Blackmore was motivated by a desire to see an end to choked-up junctions, which he found frustrating and unnecessary. Eventually, he elaborated on his original idea by developing multiple roundabouts. Two of his projects are the so-called magic roundabout in Swindon (1972) and the multi-ring junction in Hemel Hempstead (1973), which, love them or loathe them, are cunningly effective ways of moving traffic. He was also keen to improve road safety, and the mini-roundabout has indeed proved much safer than traffic lights.
YouTube has a driver's eye view of going through the Swindon roundabout. If you want to see how traffic should operate in the Swindon roundabout study this amusing diagram (reproduced below but easier to see at the link).
--jt
--jt