General election 2019: Parties splurge on Facebook ads Rory Cellan-Jones

Technology correspondent

@BBCRoryCJon Twitter Published duration 2 December 2019

image copyright Getty Images

The political parties' Facebook ads campaigns had been lively enough since the general election was called a few weeks ago - but suddenly over the weekend they caught fire.

On Sunday, the Conservatives unleashed a tidal wave of adverts. Their two themes were getting Brexit done, and improving the NHS.

At one point, the Facebook Ad Library showed that about 2,500 adverts paid for by the Conservative Party were live.

image copyright Conservatives image caption Many of the Conservatives' ads are about the party's NHS spending plans

The Liberal Democrats appear to be on an even bigger splurge . The last time I looked they had about 3,000 adverts running, many of them with an image of Boris Johnson.

The message was that only a vote for them could "stop Boris".

By contrast, while Labour has spent heavily over the last seven days , the library currently shows only 250 Facebook ads running at the moment, many with a message promising cheaper rail travel.

Many of these thousands of ads look identical when listed in the library - the claim that 40 new hospitals are to be built appears on hundreds of the Conservative adverts, and a Liberal Democrat message proclaiming "You Can Stop Boris Johnson" is repeated again and again.

image copyright Liberal Democrats image caption The Liberal Democrats' ads seek to undermine trust in Boris Johnson

But each one has been targeted at different audiences by the people who paid for them.

The Ad Library gives only very limited information about who is seeing these messages. But luckily we are getting far more detailed insights from people who send screenshots of the "Why am I seeing this ad?" message to election.ads@bbc.co.uk

This tells us, for example, that some of the Conservative NHS ads have been targeted at people in Bury, Stroud and Abingdon. They are all key marginals that are Tory targets.

Another was earmarked for males aged 35 and over in Cardiff, where one seat is a marginal.

The Liberal Democrats also appear to be targeting particular constituencies.

One advert bore the message: "Only the Liberal Democrats can beat Corbyn's Labour in seats like yours."

It was sent to people in Cambridge "interested in Conservative Party, The Sunday Times and more".

The Liberal Democrats did come second to Labour in the constituency in the 2017 election, although they still have Labour's majority of nearly 13,000 to overcome.

As for the Labour Party, its targeting strategy is more opaque.

image copyright Labour image caption One Labour ad focuses on the party's plan to cut the cost of rail travel

Many of the "Why am I seeing this ad?" messages our correspondents are sending in state that "Labour uploaded a hashed list - Facebook matched your information with information on this list".

In other words Labour, like other parties, has a database of voter information which it matched with Facebook's user data.

The reference to it being "hashed" means that the names were kept secure and could not be read by a third party if the transmission were somehow intercepted.

We don't know what parameters were set for the list.

And while we do know that the volume of ads from the Conservatives, the Liberal Democrats and Labour has surged over the last few days - that doesn't necessarily tell us who is spending most heavily.

The Facebook Ad Library report shows Labour as the biggest spender over the seven days from 24 to 30 November - which was before the other parties began their spending spree.

image copyright Facebook image caption Targeted users get information about why they have seen an ad

It says the party's main account along with that of Jeremy Corbyn spent £282,831 over the period.

The Liberal Democrats came second with £206,442 - Jo Swinson's account did not spend any money on ads over the week.

And the Conservatives are way back with £54,443 spent on ads via its own account and that of Boris Johnson.

But each ad Labour bought via the party's account cost an average £389, while spending via Jeremy Corbyn's account was on average £5,899. Presumably the adverts for the leader were shown to more people and thus cost more.

Now we wait for Facebook to release spending data for the avalanche of ads released in the last 24 hours.

What remains unknowable is what impact these adverts are having.

Certainly the messages from our correspondents are mostly negative. People complain about misinformation in adverts, about poor targeting - "I don't live in Winchester but am in Surrey Heath" - and about the whole concept of election advertising on Facebook - "more social media propaganda".

But as with all advertising, the parties are paying for it because they believe it works.

So expect to get plenty of politics cluttering up your social media feeds over the next week - and keep sending your screenshots to us.

Seen any political ads? Send them to us

Please get involved - if you get an election ad on Facebook or any social media platform, send a screenshot of it and the Why Am I Seeing This Ad message to election.ads@bbc.co.uk.