Jonathan Stott wrote:

If you want to (safely) give it a go - try it at Lewes station where a
single-track bit has been filled in with gravel.

I'm not sure if they've been surfaced over now, I haven't been there
for a dew years, but a short lenght of the filled-in Croydon bays at
Crystal Palace (Low Level) could still be seen between the two parts
of the station still iin use. One of these had a platform on both
sides of the track.