Short answer
Mostly by repeating a small number of messages many times. The Conservatives started 9,137 ads using only 452 distinct texts; one text accounted for 2,479 ads and five texts for 63% of all their ads. Labour spent the most on Facebook and Instagram.
What the evidence shows
- Labour's party, leader and candidate pages spent between £1.00 million and about £1.32 million on Facebook and Instagram, ahead of the Liberal Democrats and the Conservatives (up to about £0.9 million each).
- The Conservatives' ads were launched mostly in the first four days of December.
- The Liberal Democrats ran 7,930 ads from 174 texts. Labour and the Brexit Party spread their ads across many more messages.
- Within Labour, the top tenth of ads took about four-fifths of the estimated spend.
- Attacks on a rival leader appeared in more ads in 2019 than in 2017, but that rise came from the Brexit Party, almost all of whose ads attacked Jeremy Corbyn. Within parties that advertised in both elections, attacks did not rise.
Caveats
Spending figures come from Facebook's Ad Library Report and cover the main party, leader and candidate pages; five days of the report were missing and are estimated.