The most recent and publicised case was back in 2011 when a chap sued Coventry Council over this very thing
http://www.dailymail.co.uk/news/article ... heels.html
In most cases, the council will impose their statutory section 53 defence, but the courts are starting to see through this now and have intimated that many councils are using the statutory defence as their get out of jail free card rather than actually repairing the road.
If you see a significant pothole, I would be inclined to report it on the basis that once it is reported and they are aware of it, the defence becomes weaker in the event of a crash, and if it is not repaired within a reasonable period of time, then their liability could increase substantially, which in the case of a catastrophic or fatal crash could run into many millions.
I know that in some areas, their inspection records have been marked up as having carried out an inspection, but in reality it was simply a paper excersise and nobody went anywhere near the site.
The same rule applies in something like diesel spillage.
It is unreasonable for the local council to be aware of every spillage, so the first person who comes off on said spillage might have a claim against the MIB under the untraced scheme but is unlikely to be successful in a claim against the council. However, once it has been reported, then if the council fail to react promptly and in a reasonable time and/or without reasonable excuse, it becomes strict liability and they become liable for each and every crash that occurs subsequently.
It is better to arrive 30 seconds late in this world than 30 years early in the next