Tim Bale is Professor of Politics at Queen Mary, University of London. He is the author of The Conservative Party from Thatcher to Cameron, and co-runs the ESRC Party Members Project (PMP), which aims to study party membership in the six largest British parties.

Party membership figures should always be taken with a pinch of salt – or in the case of the Conservatives, some might suggest, a whole spoonful.

Brandon Lewis, now the head honcho at CCHQ, has clearly decided that valour is the better part of discretion and has announced that grassroots Tories now number around 124,000.That, as Paul Goodman noted earlier this week on ConservativeHome (which, incidentally deserves a medal for its tireless campaigning on the issue) is significantly more impressive than the figure of 70,000 that was being bandied about by the media a few months back, even if does represents quite a drop on the nearly 150,000 announced in 2014 by the then Party Chairman, Grant Shapps.

The problem, however, as Paul also said, is we don’t really know how the figures are compiled, meaning we aren’t really in a position to know, firstly, if they’re very accurate and, secondly, if it’s reasonable to compare now with then.  Regular readers of this site – and particularly those who are also grassroots footsoldiers  – will know that, for an organisation that can claim to be Britain’s richest political party, the Tories aren’t exactly a model of efficiency.

And this is especially the case when it comes to servicing and even recording its membership.  Partly because of a long history of tension and turf wars between local constituency associations and CCHQ (and its predecessor, Central Office), the Conservative Party lacks the kind of robust, exhaustive and exclusive centralised system which allows its rivals (most obviously, perhaps, the Liberal Democrats) to file accurate and up-to-date membership totals with the Electoral Commission along with their annual accounts – something the Tories singularly fail to do year after year.

One of the aims of William Hague’s Fresh Future reforms of the late 1990s was to create a truly national membership system. But it’s an aim that, even now, and despite various promises down the years, has never been fully realised. So it’s not altogether clear exactly where (centrally, locally or both) the details of those who join (or, indeed, those who subsequently leave) are held. As a result, there is both missing and duplicated data, and there are also time lags – all of which means that any attempt to collate a total membership figure is currently as much an art as a science.

No doubt Lewis and his staff have done all they can to get the numbers that he released this week as accurate as possible. But they have to be seen as an educated (and perhaps only a best) guess. Nor, I suspect, would those carrying out the exercise be able to confirm that it was conducted using precisely the same methods that were used three or four years ago, meaning that any attempt to identify a trend (something the admirable Commons’ series of briefing notes on UK party membership is always particularly keen to do) is fraught with danger.

This isn’t just an irritation to those of us who like to know what’s actually going on inside parties. It’s also got major practical and political implications for the Conservative Party itself – and, indeed, for the country as a whole.  For one thing, it needs to know who and where its members are if it is to mobilise them more effectively than it clearly did at the last general election.

For another, sooner or later the party will hold a leadership contest in which its members (rather than being by-passed by a short-circuited parliamentary process as they were in 2003 and 2016) will actually get to decide the winner.  Whoever Tory members choose in that contest is highly likely become not just the Party’s leader but our Prime Minister, too. All the more important, then, that we have an accurate sense of how many and who those members are.

That is going to require a serious effort – and almost certainly some serious spending – on the part of CCHQ. It will also involve some potentially bruising bust-ups with Associations that (in many ways quite rightly) value their autonomy. Even more awkwardly, putting things on a proper footing may well produce a definitive number that the party won’t exactly be able to boast about. Still, you’ve made a start, Mr Lewis. Let’s hope, unlike some of your predecessors, you can see it through to the end.