restrictions on supply are the most important factor outside central london. There is no reason why sufficient housing could not be built in Kent or Oxfordshire to meet new demand.
House prices in the UK, particularly in the south of the country, have been increasing above inflation for several decades. There was only a relatively brief decrease in average values following the financial crisis. This is because the major driver of house price increases in the UK is the limitation of the supply of developable land caused by Britain's inflexible and outdated planning system.