Although she fails to go with the Blue Nun part of the story, Jancis Robinson MW has also written about the spurious data about wine sales above £10.
It must be said that spreading the rumour about others spending a lot on wine could be useful. As Mark Earls points out on his 'Herd' blog, we are heavily influenced by what others think and do, so "if everyone else is paying £10, then maybe I should too" might have an effect.
Maybe some independent merchants could do a follow up on this story and recommend a series of £10 wines that would demonstrate how much better wine was at this price.
I quite like the idea of copying the diamond marketing concept, you know the one ... "everyone knows you should be spending at least the equivalent of one month's salary on your diamond engagement ring" (I noticed that a few years back they tried a campaign that said two months!!). If style mags and newspapers picked up on Decanter editor Guy Woodward's comments and established £10 as the minimum to spend on a wines as a present or for a dinner party, it would at least raise the bar (so to speak).