By Chris Dorrell The UK’s economic problems are deep and complex, but if there is one thing that could boost the economy without putting further pressure on the government’s finances, it is reforming the planning system. Britain’s overly restrictive planning regime is one of the key factors behind the UK’s single largest economic issue: stagnant productivity growth. While the failures of this cumbersome regime are holding back many sectors in the economy, housing is the most obvious victim. New figures out yesterday showed that the average UK home is now worth 8.3 times the average annual sala…