It may be over nine years since this article was published in the Independent but it is still relevant and current.
30 mph for 80 Odd Years
The 30 mph speed limit was introduced in 1935. In 1934 after a period of 30 years with a speed limit of 20mph the limit was derestricted. Between 1934 and 1935 the derestricted roads brought about a spate of deaths and the government decided to introduce the 30 mph limit in built up areas. Just before the speed limit was introduced there were only one tenth of the cars that are on the road today.
I suspect that you were, perhaps, 10 times more likely to see a cart with a horse in ‘The Street’ in 1935 than a car.