I'm afraid we don't have a general map key, only the one for the bike path overlay.
This just highlights cycle routes like national cycleways. I am actually looking for the map keys which help identify things like hostels places of interest just like on an ordinary os map
Hi John - there is a key for the Bike paths. You can view this by clicking the bike symbol in the Map Types box at the top of the map.
Is there anywhere you can locate the map key