On Monday, a six-week balloting exercise will come to an end at Bradford & Bingley Building Society. It will announce the result of a vote among its 2.5 million members on whether the society should demutualise.
Experts believe the decision will determine whether the demutualisation bandwagon is derailed or (following last year's negative vote at Nationwide) is gathering pace and dragging other societies along with it.
B&B has pulled out all the stops to mobilise voters. More than 1.6 million votes are believed to have been cast, the highest turnout for a society challenged by one of its own members.
The result is set for a nail-biting finish. A society spokeswoman said: "We remain confident about the outcome, although we are not complacent."
The argument, as always, is about money. Would you rather have hundreds of free shares worth up to pounds 1,500 or lower mortgage costs and higher savings rates?
The lure of free shares is hard to ignore. Former members of Halifax, the society that converted in June 1997, received an average of 330 free shares each at demutualisation. The shares, worth 736 pence on flotation, are today almost 900 pence each.
Even more enticing is the fact that the total amount of dividends already paid out - or about to be in the next six weeks - amounts to about pounds 1 per share. In effect, someone with an average shareholding is in line for a payout of pounds 330; they are, moreover, sitting on about pounds 3,000 of free shares.
A Halifax spokeswoman says: "From the point of view of our shareholders, conversion has been an absolute success. there is no way that we would have been able to pay that much surplus capital to our members in the form of improved benefits."
Alliance & Leicester shares have done better than Halifax's - rising 72 per cent to 880 pence and worth pounds 2,200 to former members - although their dividend payout to date is pounds 112.
There is another fact to take into account. Of almost 7 million Halifax members who received free shares, barely 3.5 million are left; the 2.5 million Alliance & Leicester shareholders at launch are barely 1.1 million today.
Meanwhile, pro-mutual supporters argue, their customers are left paying for the flotation through higher mortgage charges and lower rates paid on their savings accounts.
This was underlined recently in a survey by Which?, which found that someone with an pounds 80,000 mortgage with Bradford & Bingley would have saved pounds 719 just between 1996 and 1998 compared to the average variable rate charged by eight other former building societies.
The society also paid an average 1 per cent more interest on pounds 3,000 held in a tax-free Tessa account than the average of the same eight converted societies - equal to pounds 150 in extra interest over a Tessa's lifetime.
Adrian Coles, director general at the Building Societies Association, says: "The reason why societies do so much better is that, unlike converters, they don't have to pay dividends to shareholders. That means they can pass on the benefits to all their members."
However, an Alliance & Leicester spokesman points out that headline rates are not always a reflection of good value: "Most new borrowers are on fixed, capped or discounted deals, where every lender will have its own atttractive rates, not just the mutuals."
At the same time, despite Bradford & Bingley's competitive prices, the cheapest variable mortgage rates at present come from Egg , Legal & General, Bank of Scotland and Standard Life Bank, three of which are part of publicly- quoted companies and only one (Standard) is mutually-owned.
For members at Bradford & Bingley, the verdict is due on Monday. Irrespective of their decision, the lure of free shares is probably too attractive for members of other societies to pass up. This will definitely not be the last vote on the issue.