New Localism Bill increases planning powers

[Philofacts]

The ability for local planning authorities to take enforcement action is currently time-limited.  If a house or extension has been built without planning approval or if there has been any change of use,
the rule as it stands means that the local planning authority cannot take enforcement action after a period of four years.
When a condition of an existing planning permission has not been discharged or complied with, the authorities have up to ten years to take action.

The new Localism Bill will allow local planning authorities to take enforcement action at any time after it becomes aware of an unauthorised development.
Buyers of homes will now become liable for any unauthorised development by the previous owners, whether they knew about it or not.

[Banjo]

That will stop all those people who build a house in the woods or in a field and hide it under straw bales and wait for the time limit tro run out.
Even then some have not been successful and have had to demolish once the council became aware.