At present, the Jubilee line runs 30 trains an hour at the busiest times.
Under now cancelled plans to buy extra trains, Tube bosses hoped to reach 34 or 36 trains an hour.
Next May TfL will extend the period during which the highest frequency operates from one hour to two.
Without extra trains in the fleet, it is now hoped to reach 31 or 32 trains an hour in 2019.
Learn more by watching this video of the London Assembly transport committee’s session this morning: