How come he was even thought to be a contender?

The splash leads of both the Times and the Guardian won’t make happy reading at the home office this morning. For the David Nutt resignation looks set to be followed by others raising questions over whether ministers are ever serious when they ask experts for advice.

Adding to their problems is the home secretary’s appearance with Adam Boulton on SkyNews yesterday when he appeared to totally lose it under close questioning. For the one thing you’ve got to avoid when the cameras are on you is to lose your rag and that, surprisingly, is what Alan Johnson did.

Maybe Gordon knew what he was doing when he made the man being talked up as his successor the home secretary. This is a job that’s become a grave-yard for Labour politicians – just think of Jacqui Smith, Charles Clark and David Blunkett to name but a few.

Johnson’s response was unexpected given his apparent sure-footedness in the past. His easy self-deprecating style has usually defused most situations and generally he has had a good press. When he got the job in June I thought it was a good appointment and perhaps a platform for greater things.

The problem he’s got now is that the story could dominate at least one more news cycle as other members of the committee follow the lead of their chairman and resign as well.

It’s a natural for Cameron at the next PMQs and you can see him using it to draw conclusions about the whole government being in a mess.

Johnson’s still favourite in the betting to succeed Brown but that, surely, won’t last.

Mike Smithson