The other point is that there is an acknowledged shortage of housing in London / under supply of housing. So if there are unused shops there will be greater and greater pressure to convert them into flats. In other words if you want a parade with shops / restaurants etc then they need to be used, or they will be lost.

If a site like the Old Bank remains unused for 2 years, then the trend will be if it can't be used for a restaurant, why not convert to flats? I realise this then leads onto the question of rents, e.g. is the landlord holding out for big (or unrealistic!?) rents in the hope of converting to flats.