Here's a breezy review (by Francis Wheen) of Unfit to Rule: The Blunders of our Governments by Anthony King and Ivor Crewe. One example is the NHS IT contract: "£20 billion - enough to build three dozen general hospitals - pissed away on the whim of a prime minister who knew nothing about computers" (that's Tony Blair).
The Dangerous Dogs Act is in there and it is a good example of over-hasty legislating. But it's nowhere near as costly as the mistakes in big infrastructure projects. Some new ones are happening as we speak: Universal Credit and HS2 for example. The Labour Party has just released a double-edged sword of a report about problems with long-term infrastructure planning.
But what is the answer? In one sense the answer probably involves things like early design-freeze and continuity of senior personnel, but I mean why are those answers not already being adopted? The answer must be that there is no real answer: it is an inherent cost of democracy that projects are subject to change and cancellation if political will changes, (at best) contractors build that cost in and (at worst) that means huge wasted costs when changes occur.
The Labour report seems to recognise that democracy is the problem: "Mr Balls added: ... "The Olympics showed what can be done when there is cross-party consensus and a sense of national purpose. Now we need that same drive and spirit to plan ahead for the next 30 years and the needs of future generations."" Fair enough, Mr Balls, but a cross-party consensus means 'no change no matter what which party is in power', i.e. no democratic control over the choices at all. (Didn't we use to have a cross-part consensus on HS2 - until Labour saw how the wind was blowing?) If we all agreed what the needs for the next 30 years were then perhaps that would be fair enough - but we don't. How many Sharia Court buildings will we need over the next 30 years? How many nuclear power stations - or are we going to frack instead?
Of course, there's room for improvement etc etc. But there is a reason why 'they do these things much better in China/Singapore/take your pick of effectively one-party state'.