The ConservativeHome monthly survey is not an opinion poll.  That’s to say, the participants are self-selected, and the results aren’t weighted.  However, it is not a straw poll: those who are surveyed in one month are almost entirely the same people as were surveyed the month before.  That’s why we call them “the panel”.

The exceptions are the additions.  All of these must send a copy of their Conservative Party membership card, or provide other proof of membership, before they are added.

It is possible to believe that if the sample for such a survey is large enough from a pool that is small enough, the results will be a useful guide to the views of members. Party membership is somewhere between 100,000 and 150,000.  Our last survey drew about 1700 replies.

Our contention is that the survey is a reliable guide to trends, and a rough guide to opinion.  How does that claim measure up against the YouGov poll in this morning’s Times?

Our last monthly survey had Boris Johnson top of our Next Tory Leader question.  The YouGov survey also has Johnson at top of its poll.

We produced run-offs in our last survey putting Johnson up against Michael Gove, Jeremy Hunt, Sajid Javid and Dominic Raab.  He beat all of them.  Raab was the runner-up.

The YouGov poll puts Johnson up against all of these, plus Matt Hancock, Andrea Leadsom, Penny Mordaunt and Rory Stewart. He beats all of them.  Raab is the runner-up.

Our figures include don’t knows and won’t votes.  You Gov’s don’t.  So the percentages aren’t directly comparable, but those interested will study the tables.  At any rate, the similarity in headline finding is clear.

Elsewhere in the tables, 79 per cent of members believe that Theresa May should step down as Conservative leader. The figure in our last monthly survey was 82 per cent.

66 per cent of members back No Deal, according to YouGov.  A survey from us earlier in April found 75 per cent, though it’s worth noting the options put in our survey and in the YouGov poll were different.  It topped both lists.

Eighty-four per cent oppose a second referendum.  Our last survey question on the matter, in January, found 87 per cent opposed. All in all, we believe that this latest YouGov poll more than bears our contention out.

It’s worth adding that YouGov is the only polling organisation that we know of which regularly polls party members in this way, and we  regard it here as the gold standard in these matters.

YouGov also asks a mass of supplementary questions about the potential candidates’ competence, likeability, election-winning capacities etc, which are well worth a read. For previous articles on this site about the reliability of the survey and its comparability with YouGov, see here, here, here and here.