And if you wanted a good price, you had to give each of them a bit more business than they might naturally expect, based on their share of viewing. That seemed to be how it worked - they just cared about share.
In practice, what I remember this meaning was that, for each campaign, you would pick a contractor that would get less than they naturally should so that all the others could get a bit more. It always seemed to be Border that got a bit less. Then, you would have to explain to the dealers or retailers in Southern Scotland and Northumberland why they never saw your ads, and you would buy a slightly heavier-than-expected campaign in Scottish newspapers.
Monopolies and consolidations of power always destabilise the media logic - those arcane practices that only make sense on the inside. I've been reminded of all this while reading a spate of articles and talks about the big powers in technology: Amazon, Apple, Facebook, Google and Microsoft (although Microsoft does not always make the list, which, just ten years ago, would have seemed astonishing).
The most striking version of this was from Bruce Sterling at SXSW in Austin. He described these huge businesses as "stacks" - stacks of technology that replicate all the stuff you want from the internet, but try to keep you within their own silo. As he pointed out, they have all developed "an OS, sociality, a pet mobile device, a marketplace and internal payment system and productivity software" - and, obviously, their own proprietary technologies interact very well inside their silos. Buying a book on the Kindle is a dream, as is getting music from iTunes to an iPhone. But you can't, for example, buy a Kindle book from within the Amazon app on your iPhone.
We end up with more "walled gardens" - not just for content, but for services, interactions and behaviours. You could see the $1 billion Facebook paid for Instagram as being about stack preservation, as the Facebook stack is built on sharing pictures on the web. Instagram was starting to build a serious business sharing pictures on mobile, so the Facebook silo had to incorporate that or defeat it.
It's logical for them, but potentially troubling for users and for the overall health of the web. And it must be a nightmare for marketing people trying to talk to people via these channels. Where do you place your bets? Which stack do you back and which do you sack? Which of them is the technology equivalent of Border?