From memory...

Many or most deep tube stations have a 1 in 30 fall on leaving the station,
to aid acceleration. Some of the earlier stations have a 1 in 30 climb
before the station to aid deceleration, but the newer stations have a 1 in
60 climb because it is difficult to get a train going if it has come to rest
for some reason on a 1 in 30 climb. There is no gradient in passenger use
steeper than 1 in 30.

The steepest gradient on non-passenger track is a 1 in 28 gradient in Ealing
Common depot.