Just bloody well get on with it and start undergrounding powerlines. Yes, it'll cost a lot of money, but pretending that a) it's not worthwhile, or b) it all has to be spent in one lump sum rather than spread over 20-30 years is just silly.
Message to the relevant people/bits of government/companies in the UK :
Just bloody well get on with it and convert road signage to metric. Yes, it'll cost a lot of money, and require lots of organisation and planning, but it's about time. Other countries have managed it quite nicely, and the longer you leave it the harder it will get.