I've just been writing a chapter for a book on British Prime Ministers and Leaders of the Opposition, and I wanted to see whether unpopular Prime Ministers (or even Opposition Leaders) could win a General Election.
2005 was an exceptional election. Tony Blair's average net approval rating (-26) was lower than that for Michael Howard (-20). Suggesting that in that election, the voters based their decision on more than just their ratings of the party leaders.
Is this comfort for Gordon Brown? In the first half of 2009, Brown's average net approval rating was -33; substantially below that for David Cameron (+14) - indeed Cameron is the most popular Tory Opposition Leader since Ted Heath in the 1960s.
The bad news for Brown and Labour is that not only is their leader behind the Conservative alternative, but the gap between them is huge. At 47 points, there have only been two General Elections since 1959 where there has been anything like this gap - in 1997 (Blair's lead over Major was 73 points) and in 1983 (Thatcher's lead over Foot was 49 points).
Of course, the next six months might see a turnaround for the fortunes of the present PM, but time is running out for what at the moment looks like another a sign that a landslide election is on the cards...