At the Brecon and Radnorshire by-election, British democracy appeared as unchanging as ever.

Party activists scrutinised the count. Candidates scowled and smiled on stage. The old sports hall echoed with gossip and congratulations.

The show of togetherness disguised stark divisions. On the crucial new battleground of Facebook and Instagram, the two lead campaigns might as well have been living in different worlds - most obviously with regard to age.

Whereas the Conservatives pushed their ads at the over-55s, the Liberal Democrats focused on voters under 35, with little crossover between the two campaigns.

One series of ads run from the Facebook page of Conservative candidate Chris Davies calling for voters to "back the new Prime Minister to deliver Brexit". According to data released by Facebook, 45% of the people who saw this ad were over 65. Only 4% were aged 18-to-24.


Many of the 90 ads run from the pages of Chris Davies and the Brecon and Radnorshire Conservatives -- which spent a combined £6215 on Facebook ads in the 30 days before the election -- echoed this pattern.

A set of ads explaining that "this by-election will be VERY close" were seen by only 6% of 18-to-24-year-olds, compared to 45% of people over the age of 55.

Ads calling for "no new wind farms" and asking voters to "back farmers" were seen by double the number of over-65s compared to 18-to-24-year-olds.

By contrast, the Liberal Democrats largely targeted at younger voters. Of the people who saw a typical ad featuring local residents, for instance, only 7% were over 65, whereas 39% were under 35.

The Liberal Democrats' successful campaign to recall Chris Davies also showed ads primarily to younger voters.

The party spent £1,500 on 45 ads from a page called "Demand Better for Powys" which complained that "our Conservative MP has been convicted of making false expenses claims".

One ad describing "the judge's damning verdict on Chris Davies MP" was shown to over-55s 12% of the time and 18-to-24-year-olds 34% of the time.

Facebook asks every new user for their birthday, giving it a largely reliable record of the ages of all its 2.4 billion monthly active users - and making ad targeting by age a straightforward matter.

That's enticing for political parties, as age is a key predictor of voting intention; more than education, class or gender, according to a recent YouGov survey, which declared that "age seems to be the new dividing line in British politics."

On Facebook, however, it's just part of the picture.

Sky News' Rowland Manthorpe look at Facebook ads for the by-election

Image: Amy Shepherd from Open Rights Group

"Age is just the surface level. Other factors such as your spending, home ownership, interests, likes and dislikes, will be used to build up a detailed profile of you," Amy Shepherd, legal and policy officer at Open Rights Group, told Sky News.

"That can be used by political parties to determine how to advertise to you and indeed in fact whether to bother to advertise to you. You can target very small parts of the population with quite extreme messaging that responds to your profile."

"Political parties know exactly how to push your buttons - and once they've learnt how to push your buttons then they can target you with more extreme and polarising messaging. That's where it gets really concerning because that's how elections get shifted."

The Conservatives ad blitz in Brecon and Radnorshire is part of a much larger push on Facebook. Last week, Sky News broke the news that the Conservatives were flooding Facebook with ads featuring the newly-appointed Prime Minister.

In the last 30 days, according to Facebook, the Conservatives have spent £38,104 on 2,682 ads from its main page, mostly calling on voters to enter their name, email address and postcode in online forms - information which could all be used to enable more accurate targeting in the event of a general election.