Harold Wilson and Edward Heath are two very different men equally overlooked by history, but they were the political titans of the era in which Britain changed for ever. For ten years they faced each other in the House of Commons, and swapped in and out of Number Ten. They fought four general elections, three of which were amongst the most exciting of the century.

It begins with cheers but almost always ends in tears. Yet, as the election looms, competition for the top job grows ever more intense. Why? The hours are terrible, money so-so, job security non-existent. On the plus side, there's free accommodation in central London and probably more power over your country than any other leader in the western world. With the help of the present and previous incumbents, Michael Cockerell offers the first "how to" guide to the job of prime minister.