20mph speed limits - are they actually enforceable

[knip]

So Bristol have today "unveiled" a bunch of new areas that now have a 20mph speed limit.

I thought (ironically I learnt this at speed school ) that these were not legally enforceable as that would require the government to change the law. I was told by the people running the course that they were a guideline, and as long as you stuck to 30mph (which is the national speed limit) then the police can't do you for speeding. That's why the signs are smaller in size for example, because if they were the same size as 30mph ones, then the signs would be illegal.

I remember them saying something along the lines of "if you had a crash, they might be able to charge you with dangerous driving if they believed that to be the case, but that as long as you were within 30mph, then they couldn't charge you for speeding."

Does anyone have definitive proof of what the law says? They make it sound like we HAVE to stick to the speed limit, so most people take that as gospel and do, but is it actually the law?

Thanks for anyone's help

 

[knip]

See the police have said they aren't enforcing it

http://www.bristolpost.co.uk/Bristol-s-20mph-zones-enforced-police/story-19668468-detail/story.html

Mayor has said this

If you work or live in central Bristol you’ll see that we’ve introduced a 20mph limit on most roads that were previously 30mph in Cabot, Cotham, Clifton, Clifton East, Bishopston and Redland wards from today (21 January).

Following two successful pilots, this is the first of six 20mph schemes to be rolled out across the city over the next 12 months.

We're working closely with our police partners to ensure people accept and understand why they are being asked to drive at 20mph and will be rolling out a number of community speed watch programmes where local people and police monitor speeds.

Driving at 20mph has been proven to significantly reduce the risk and severity of road accidents and impact of speeding on local communities.