What does a spad do?

The Damian McBride affair has shed the spotlight on the murky world of special advisers.

Here the BBC explains their role in government.

To see their work dramatically portrayed in full Technicolor go and see Peter Capaldi’s excellent performance of Malcolm Tucker (not, Capaldi claims, modelled on Alastair Campbell) in the new film out this week “In the Loop” - described in today’s Guardian as “funny, vicious and delicious”.