General Election 2019: Which non-party groups are sending you ads?
As the messages keep pouring in to our election ads project one thing stands out - just how many non-party groups want to get involved in this election campaign.
In the last few days we have seen ads from new anti-Labour groups City Future, Capitalist Worker and Reignite.
A group called Advance Together is urging voters to abandon the Conservatives.
And the Open Rights Group says both Boris Johnson and Jeremy Corbyn are building profiles of voters with their personal data - and says we should all be worried about that.
But the most intriguing new entrant to the Facebook election campaign is called 3rd Party Limited.
We have been sent ads paid for by this organisation for two very different campaigns.
One ad features a photo of environmental campaigner Greta Thunberg and urges people to vote for their local Green Party candidate.
It was targeted at people interested in Greenpeace and Oxford University, living in Didcot in Oxfordshire.
The same ad was also sent in by someone in the Cambridge constituency.
The other ad is for a group called Save Brexit which wants people to vote... to save Brexit. It was very broadly targeted at people aged over 18 living in England.
So what is 3rd Party Limited and what is going on here? Wired Magazine did some digging and found out that the company had been set up by Thomas Borwick, formerly chief technology officer at Vote Leave during the 2016 referendum campaign. What's more the Green Party was not at all happy about these ads.
The Greens say they have not been contacted by Mr Borwick or his organisation and have no knowledge of his aims. A spokesperson told the BBC: "Any Green Party adverts are always clearly labelled as paid for by the party as per Facebook rules. We would always encourage voters to check the source of any information they are receiving due to the large amount of disinformation currently circulating on the web."
It has been suggested that 3rd Party's aim is to cause mischief rather than support the Greens, by persuading anti-Conservative voters away from more electable Labour or Liberal Democrat candidates.
If so, the two Green ads we have received seem poorly targeted. Didcot is in the Wantage constituency where the Conservative Ed Vaizey, who is standing down, had a majority of more than 17,000 over Labour in 2017. The LibDems were a distant third. Cambridge was won by Labour last time with a majority of more than 12,600 over the Liberal Democrats.
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We emailed 3rd Party Limited seeking information about the donors behind the ads and the strategy behind their targeting.
We received a reply saying all reportable donations would be reported to the Electoral Commission: "Green causes are very important to some of our patrons, and our objective, therefore, is to encourage voters to give the Green Party its strongest-ever showing at the ballot box."
The ads, said the email, were targeted at "areas where our research indicates there are a high proportion of voters who care about environmental issues".
The statement expressed surprise that 3rd Party's efforts were not welcomed by the Green Party: "If the Green Party feels that voting for their candidates is bad, you would have to ask them why they've decided to stand."
But the mystery remains. If 3rd Party and its donors were so keen to help the Greens why did they not simply hand over some money directly to the party, or at least get in touch to discuss where ads might best be targeted?
I texted Thomas Borwick with that question.
He replied: "Third parties are not allowed to work with the central campaigns."