A month after new, super-stringent speed limits were imposed across the town, Oxford seems to have as many notices informing drivers that "it's 20 for a reason" as it has actual signs for the new 20mph limit. I must admit that I'm still looking for it.

It's easy to make a reasoned argument for well-applied 20 zones, and it's not one I would ever stand in the way of. Oxford's problem is the new limit's very universality. Which, at a stroke, has completely removed a 20-zone's ability to emphasise particular dangers or risks.

The nearest 20 road to me has got no houses or driveways on it, and has already been traffic calmed with a pair of 'pinch points' and two humped Zebra crossings capable of stopping a Panzer Tiger in its tracks. Yet it's been slapped with the same 20 limit that protects the narrow residential streets around the local primary school.