For according to the Common Law a custom must have six attributes. In the first place it must dating from time immemorial, which has been conveniently fixed by the Common Law as when our Lord Richard returned from Palestine, in 1189. Now, obviously, when our Lord Richard returned from Palestine, the amount of mercantile custom existing in England was of the very slightest description, and if one is to trace all one’s mercantile customs back to his return from Palestine, or if a custom is liable to be defeated, by proof of a later origin, very few mercantile customs can possibly be proved. The custom must be continuous from that date in the second place. In the third place it must be universally acquiesced in. In the fourth place it must be reasonable. In the fifth place it must be certain; and in the last place it must be binding.

T.E. Scrutton
Sir Thomas Edward Scrutton
28, August 1856– 18, August 1934
The Elements of Mercantile Law, 1891, p 19.