Jeremy Paxman once famously described it as ‘a concept as easy to bandy about and as hard to explain as Heisenberg’s uncertainty principle or the doctrine of transubstantiation’.
Picture the scene, a demolition site where grass now grows on the mounds where terraced housing once stood and street lamps denote the century old layout of an urban settlement. Pinned up on the notice board is a grand vision – a masterplan for redevelopment.