One of the best jokes about Government reshuffles is that they are like 'rearranging the deckchairs on the Titanic' for Prime Ministers facing troubled times. They often result in few substantive changes of direction and just cause disruption.  Blair and Brown were constantly moving ministers around and restructuring departments. Cameron and Clegg, to their credit, have made few changes at Cabinet level since 2010 and have generally allowed junior ministers the longevity needed to learn their brief.