Walker is a councillor for Bradley Stoke in South Gloucestershire and a former mayor of Bradley Stoke. He has defected because of bullying in the local Conservative Party and because of the Tories' "ill targeted" cuts and support of the EU.
A spokesman for Bristol & South Gloucestershire Conservatives said that Walker has let down the hundreds of people who voted for a Conservative last year. I can't seem to find any condemnation of David Campbell Bannerman's defection the other way last year on their website or in a Google search so it must only let people down when it's Tories defecting to UKIP. Which is unfortunate for Bristol & South Gloucestershire Conservatives because it's happening every other week at the moment!