@Chris Miller
"But it would be simply idiotic for government to chuck £5 billion of our money at a scheme to provide extra bandwidth for which there's no demonstrable need."
Think yourself lucky. In my country (Oz) they're chucking $43bn at it. Bigger country admittedly, but over 70% of the population live in only 10 cities/metropolitan areas. Plus instead of doing FTTC then upgrading to FTTP at a later date they want to do it all upfront and hence get gouged on the prices from contractors. By all accounts from Tasmania (the test case) it doesn't seem to be working that well.