IT'S become a ritual eve-of-conference photo-op: Alex Salmond posing with the SNP's latest eager recruit.

So it was no surprise yesterday to see him welcome Elysee Ahmed-Sheikh to the party, as fellow members prepared to gather for their two-day get-together in Inverness. It was even quite predictable she just happened to be a newly referendum-enfranchised 17-year-old.

What did raise eyebrows, though, was the number. Elysee is the party's 25,000th paid-up member. A decade ago SNP membership stood at 9450. It rose steadily to 13,200 in 2007, when Mr Salmond became First Minister, but has exploded since then. The tally was 15,097 in 2008; in other words they've added just short of 10,000 members in four years.

This, of course, is great news for the Nationalists and contrasts sharply with declining numbers in the other main parties. It has created headaches. Just what does a political party do with such a sudden influx of new recruits, most of whom have little or no previous experience of activism? That is one of the big questions party chiefs are trying to get to grips with behind the scenes in Inverness this weekend.

The answer is very firmly not an old-school diet of dreary branch meetings in draughty church halls where a discussion about the common agricultural policy is followed by a desultory pint in the pub. If you're lucky. Instead the SNP's new recruits are bombarded with personalised texts and emails from Peter Murrell, the party chief executive, Nicola Sturgeon and Mr Salmond.

They receive information on the party's message of the moment and are asked to spread the word. They are encouraged to join campaign events in their area and, if there isn't one, start organising it. They are asked to file information about you, if they think you might be sympathetic to the cause, on the SNP's voter database.

Remember New Labour MPs in the late 1990s and their pagers constantly bleeping with "the line to take"? It's not dis-similar but in the modern SNP it goes further and extends not just to elected politicians but the newest recruit.

"Direct mobilisation" it's called and this weekend party strategists will be discussing how to get even more from their recruits.

As one senior figure put it: "One of the problems the party has had to deal with is the number of people who are really new and really enthusiastic. It is not normal for a party to have such a sudden uptake in members and people wanting to do things. It's a challenge."

While Angus Robertson, the party's elections co-ordinator, and colleagues wrestle with that behind closed doors, Mr Salmond will take centre stage today.

With the referendum date (September 18 next year, in case you hadn't noticed) unveiled, he will use his keynote speech first to fire up the party faithful and, secondly, to step up the effort to persuade a largely unconvinced Scotland to vote Yes. Iraq, Trident and North Sea oil will all feature heavily as he focuses on what insiders call the "why" of independence.

With 18 months to go, the plan is to show that Scotland needs to be independent before moving onto specific policies and how the new state might work in practice. For that we'll have to wait for the white paper in November but the SNP are well aware they'll have to create some momentum by then.

Their opponents know this and are already trying to spoil the party, demanding answers on SNP plans for a currency union with UK, an independent Scotland's membership of the EU and the proposed Scottish Defence Force.

"We now need the details," Better Together chief Alistair Darling said yesterday. The pressure is sure to mount but today, at least, Mr Salmond will stick to his own script.