The real full time membership figure will be higher than 59,000 or so. There may be accounting units other than the 674 we have identified. And if, for example, half the 386 units who haven't declared are roughly comparable to the 139 who have, full-time party membership would remain well above the 100,000 mark.

The Daily Telegraph and the Sunday Times (£) both burrowed into the Electoral Commission's records recently for details of Party membership figures. It was only a matter of time until a full calculation of the data was carried out, and this site has made one based on last year's figures.

However, it seems to me more likely that most of those 386 units are in the same ball park as the 143 which didn't give the Commission precise membership figures. It's therefore very hard to see where the Party would get the extra 40,000 or so full-take members that would keep its membership above 100,000.

Of course, membership isn't the be-all and end-all. If Associations with their traditional membership structures were being replaced by networks of non-member supporters, the decline (common to all the main parties) wouldn't matter all that much. Grant Shapps's Team 2015 initiative is evidence of such new thinking, and the Chairman will be picking Jim Messina's brain.

Unfortunately, however, such networks are the exception rather than the rule. CCHQ is well aware that those that there are not replacing the members who are dying or leaving. I argue in the Times today that to face up to the scale of the problem is to begin to solve it - and that means the release by the Party of its own full membership figure (especially if it doesn't like ours.)

My sense is that Shapps, who is at ease with social media and open to new thinking, appreciates that refusing to release a membership figure isn't a sustainable position. The claim that CCHQ doesn't have a working figure isn't credible. It will know the number of ballot papers issued for the recent European election selections.

However, the keys to releasing a figure are in Downing Street, not CCHQ. It's inconceivable that the latter would issue one without getting permission from Number Ten first. And David Cameron will not want to read headlines showing that membership has fallen by up to two-thirds since he was elected leader.

None the less, the next election and future ones can't be won without a presence on the ground. The Eastleigh by-election, in which MPs and members came to canvass but found an absence of reliable returns, was sobering - and the seat's situation is not unusual. The time for debate about the future of membership is now, and disclosure of the figure is an essential part of it.