I use a crib sheet .... not because I don't know the song but because I am at an age when the memory plays silly tricks.

I would rather have the words at the ready than suffer the embarassment of getting halfway through a song (that I have probably been singing for the past 20 years) and suddenly not be able to remember ...a word or a line or a verse.

Fortunately the folk clubs I go to are more understanding than yours.