As a teenage enthusiast, I remember doing the Kenny O - East Croydon XC on a One Day Travelcard, Zones 1-6. It felt quite exotic. Great 47 thrash for a London kid raised on a diet of EMUs.
Likewise. The only bad thing is it would run slow lines most of the way from East Croydon to Clapham Junction.
I used to spend a large part of the summer holidays in the signal box at Kensington Olympia after asking to look around. The amount of porn mags the signalmen had in that box was mind boggling for the 14 year old me.....