First the good news, and then the bad. To be honest, both bits of news are fairly bad. Ad blocking was slightly down in 2017 compared to the year before, according to the Association for Online Publishers (AOP). However, it's still costing the average publisher £630,000 per year, and the overall cost to the entire publishing industry is increasing too.

The Association's Ad Blocking Audit covers 14 of the country's largest publishers, including The Telegraph, The Guardianand Condé Nast. Although ad blocking was down from 31.7% of ad impressions in 2016, it was still at 29.9% at the end of 2017 -- let's call it 30%. So that means that around 30% of ads that were trying to make it to a reader's desktop were blocked.

The picture is slightly better on mobile devices, where 1.3% of impressions are blocked -- although that is up from 0.7% the year before.

In total, across both channels, the ad-blocking rate is 11.6%. Presumably, that means just over one in ten are blocking ads, but it also means that those people are consuming more content than average if 10% of ad-blocking readers are giving rise to 30% of impressions being blocked.

Although things are getting slightly better, the AOP's major warning is that few publishers are keeping an eye on ad-blocking rates and the implication for the bottom line. Without knowing the extent of the problem, the conclusion is that publishers don't put themselves in a position to prioritise tackling it.

So AOP has done the sums for them and it reckons that the cost of ad blocking is actually up year-on-year to GBP14m in 2017, compared to GBP10.8m in 2016. Clearly we are talking about quality inventory here, which is being valued at a premium nowadays and so the overall cost of missed advertising opportunities is higher. This works out at around GBP630,000 per publisher per year.

Now, let's admit one thing up front. Some publishers deserve to have their advertising blocked. They put units across editorial, move spots around to encourage accidental clicks, and basically get in the way of the reader. This has to stop, and the Coalition for Better Ads has some good advice. It's pretty much common sense and a call for publishers to use ad units that don't get in the way and don't blare out video automatically as soon as a page is loaded.

Once this is done -- once sites are made less annoying -- it's time to take the fight to the ad blockers. I've said it before, and I'll say it again: publishers have absolutely nothing to lose through blocking digital shoplifters. The only downside is that overall traffic figures may fall, but that is a vanity metric if it includes people who don't pay their way.

Some publishers are already fighting the good fight, but it should be the accepted norm. If an ad blocker visits a site, they shouldn't expect to get free editorial without consuming ads. There is a clear exchange in free online publishing, and if one side isn't keeping to the bargain, it's time to switch off the supply until the ad-blocking software has been disabled. It really is that simple.

I think the AOP has a good point that maybe publishers aren't aware of the full cost of ad blocking, and hopefully this latest report will bring it home to them. Digital shoplifters are costing them an average of £630,000 each. If that is not enough reason to stop serving up free content to people dodging ads, then I have no idea what is.

It really is time for some online publishers to grow a backbone and say enough is enough. Block our ads, and you block our content too.