Here's why right wing parties don't like the euro: A large block sharing a current and interest rate will not be able to use exchange rates to even out geographic differences. A group like the Conservative Party don't have any other mechanisms for influencing the economy, so the euro naturally doesn't make sense. The left of centre parties are happier to micromanage. They understand that you can put money in specific areas by local regeneration, or by building infrastructure. What's more, the lack of currency exchanges empowers the individual and takes the big banks out of business decisions. Moving the private sector out of people's lives, and being able to reduce the effects of the market on government policy is irresistable to these political parties.
That's what I think anyway. And what's more I think that's what the Third Way is about: Not using government money to support industries at the end of their life cycles or subsidising ventures that the markets would never allow (like the old socialist parties), but using that money to build permanent infrastructure that brings in and uses the leverage the markets can bring.