I back call by @ATCooperNo10, co-founder of British Polling Council & ex No10 that the CON incumbency polling be published

— Mike Smithson (@MSmithsonPB) November 21, 2013

First time incumbents saw a bigger boost 1.6%

The above data is from a post-GE2010 analysis by Prof John Curtice, Dr Stephen Fisher and Dr Rob Ford and shows how CON incumbents did compared to the overall increase in the party’s GB vote share.

As can be seen the biggest increase was by CON MPs defending their seats for the first time. The overall increase in the GB vote was 3.8% while they had an average increase of 5.6%.

While this is nowhere near the numbers that were being blogged about and Tweeted yesterday there is no doubt that this effect can help incumbents defending for the first time.

At GE2015 there could be well over 100 CON MPs in that category – a large proportion of them in the marginals.

But the figures are nothing like those revealed by Dan Hodges yesterday quoting a senior party source.

There is a way of solving this – for the poll to be published. This has happened before – the precdent has been set. During the Gordon Brown honeymoon in Augst 2007. CON private polling was being talked about by the party which led to calls for publication which is in fact what happened.

In 2007 Andrew Cooper was boss of Populus which carried out the polling for the Tory party. I don’t know who did the survey referred to by Mr. Hodges but it should be easy for the party or the pollster to make the details public.

If the incumbency effect is anything like the scale reported then that would change all our views of the GE2015 outcome.

Mike Smithson

For the latest polling and political betting news

Follow @MSmithsonPB