We've had rumours, estimates, surveys and guesswork about what's going on behind the Times paywall - now finally we have some hard facts. Times Newspapers says 105,000 customers have paid to visit the Times and Sunday Times websites since the paywall went up four months ago, while another 100,000 have a subscription to read the papers online as well as in print.

So does that add up to a success likely to be copied by other papers? Rebekah Brooks, the chief executive of News International, says this is an encouraging start, and the Times' editor James Harding told the Today programme it was the first time in more than 200 years that a paper had managed to get anyone to pay for a format other than print.

The real test of this great experiment is whether it will deliver more revenue than was available to the papers when their content was freely available online.

There are still some imponderables. We know that the 105,000 includes those who have paid for the more expensive iPad app, or to read the papers on Amazon's Kindle but we don't know the split. We are also unclear just how "sticky" these paying customers are - in other words, whether or not they renew their subscriptions at the end of each week or month.

We do know that around half are paying monthly - that's £8 for the website or £10 for the iPad app - and the rest are paying £1 for a day's access. By my very rough back-of-the envelope calculations that adds up to annual revenue of around £7m.

On top of that there will still be some advertising revenue, and with 100,000 paper subscribers having activated their digital editions, the newspapers have a total online audience of 200,000.

Now, once you try to work out what the size of the Times online audience was before the paywall went up you enter the murky world of web statistics. So by one measure, which looks at traffic to a website, the Times used to have a global audience of more than 20 million a month. But Nielsen, which uses a panel to measure web audiences much as it does with television viewers, reckons the true figure in the UK was 3.1 million.

So if we assume that much lower figure is accurate then the Times has suffered a drop in its online audience of more than 90%. But those who remain will be more valuable to advertisers - a study by Nielsen found they were reading more of the paper and tended to be better off than the passing trade which used to skip through the free website.

With a paper like the Guardian now earning around £40 million a year in online revenues, I think it's safe to assume that Times Newspapers has yet to achieve the same revenues from its paywall experiment that were available when its website was free. That's not to say this adventure has failed. The Times has shown that there is an audience, albeit small, willing to pay for digital content, and other newspaper groups are rushing to imitate parts of the experiment, notably the use of tablet computers as a paid platform.

One thing though did strike me about James Harding's interview on the Today programme this morning. He said his journalists' fears that they might be cut off from the online conversation had proved groundless. Really? That's not what I've heard from at least one reporter, frustrated to see rivals enjoy all the online buzz around their stories now denied to a journalist hidden behind the paywall.

And when there was a brief chink in that wall, allowing anyone in for free for a couple of hours, Times columnist Caitlin Moran encouraged her Twitter followers to rush in and grab what they could.

Still, as Mr Harding will no doubt point out, these are very hard times for the newspaper trade, and good journalism costs money. Maybe the Times great experiment can prove that online readers value the words of Caitlin Moran and her colleagues so highly that they are even prepared to pay for them.