I found a bunch of keys on a key fob on the top deck of the 205 bus heading eastbound. I got on at Euston station. The keys were on the last pair right hand seats before the stairwell.
(Nat on 04 Feb 2022)
When: 19 Feb 2020
Where: Euston(51.5281° N, 0.1332° W)
Lost a large white cardboard envelope on my way back from The Strokes gig, it also has a signature on it. Most likely left it on the Hammersmith and Circle Line between Euston and Paddington, this would have been around 11pm.
Could one of these be yours?