As well as being an arch-civil-libertarian who disagrees with much of the shadow cabinet's approach to terrorism and security, David Davis is an arch-plotter. He knows how to undermine a leader. When William Hague was in charge of the Tories, Davis frequently outshone him with powerful scrutiny of the government from his perch as chairman of the Commons public accounts committee.
Davis - a climate-change sceptic who has warned against "hairshirt policies"- can be relied on to use every summer's "silly season" to raise his profile. Some suspect that part of the reason he resigned from the shadow cabinet was that he could not stand serving under the man he nearly beat to the leadership, David Cameron. It should not be forgotten that Davis was in the final two when Cameron became leader in 2005, and that he got the better of Cameron in a BBC Question Time debate. His leadership ambitions may well reawaken.