British Airways has long offered a “Twilight” check-in facility at London Gatwick airport whereby passengers travelling on flights scheduled to depart before 13:00 can check-in their bags from 16:00 to 22:00 the day before.
We’re not quite sure how new this or whether it is just a trial but, as of Wednesday 5 February 2020, the BA website has advised that Twilight check-in is available at London Heathrow Terminal 5. This is currently available from 18:00 to 21:00 the day before.
It should be noted that it is a standard requirement that all passengers in a booking are present at check-in for Twilight check-in. Also, your bags cannot be recalled so only use it when you are certain you don’t need your bags until after your flight!
This facility may be withdrawn at any time. It may also be temporarily suspended during periods of operational disruption – in which case it’s probably best not to use it!
BA also currently offers a Twilight check-in facility at Edinburgh airport. This is available daily from 04:00 – 20:00 (04:00 – 18:00 on Saturdays) for flights departing before 09:30 the following day.