The measure of success for a Leader of the Opposition must really be a straightforward one – winning a General Election. For a Prime Minister there is a bit more to it. Thus for Tony Blair simply winning three General Elections does not mean that he can claim to be as successful as Margaret Thatcher who managed the same score.  We have to take into the equation what they actually did. But it is hard to deny that the 1997 General Election result showed that Mr Blair was a successful Leader of the Opposition.

A new volume British Conservative Leaders considers the varying fortunes of Conservative Party leaders. Interviewed for the book William Hague points to the test for a Leader of the Opposition in seeing the Party’s strength in local government increase:

He says:

“Institutional capacity in local government is really important. Active and numerous councillors with a ward-level organisation are important for fighting campaigns. Facing a long-term challenge, I gave a lot of attention to party recruitment in local government. I spent, what would have been for most leaders in those circumstances, an excessive amount of time on local government. But the Conservative Party had gone down to being third in the number of councillors in the UK. The Conservative Party was third. I think by the end of that parliament we were back to being the biggest party in local government.

“Now, strength in local government happens almost of its own accord in opposition, but not entirely of its own accord. You need to put some time in. I spent a lot of time going around the country saying that we had to put in a full slate of council candidates and put a national effort behind local campaigns.”

Ed Miliband can claim to have narrowed the gap among councillors. In 2010 there were 10,088 for the Conservatives against 4,733.  The current tally is 8,766 for the Conservatives and 6,873 for Labour. Being ahead on the number of councillors is a necessary – but not sufficient – hurdle for a political party to gain power in a General Election. Labour were ahead on councillor numbers in 1992. The Conservatives were ahead by that criteria in 2005. Both lost the General Elections. But in 1979 and 2010 the Conservatives had a clear lead in terms of councillors. Labour were in 1997.

So it is a key challenge. We will get a bit of clue how Jeremy Corbyn is doing as the Council by-elections dribble through each week and a much better test in May next year.