There are two issues here. Where electricity needs to be routed through a national park there is a strong case for buried cables. Although this is much more expensive, aesthetic considerations should surely win the day and the call for pylons that are 33% smaller is no bad thing. The second issue is reducing the need for as many pylons by encouraging more emphasis on local or microgeneration of electricity using renewable technology such as wind turbines and solar panels. This is the focus of the 'smart grid' recently backed by President Obama in the USA. It is difficult to argue with the idea, but it is making it happen that will be difficult. Persuading individuals and companies to invest significant sums for future gain is never easy, especially in the current economic climate.
According to this Guardian article, the cost of linking new wind turbines and nuclear power stations to the National Grid will be about £4.7bn. The National Grid themselves quote a figure of £9bn for the cost of changes to the network. More on this story here from businessGreen and the Daily Telegraph.