One can imagine having a procedural rule that anything ambiguous should be treated as the Taj Mahal unless we see that it is labelled "fog"…The motorist replies: "What sort of rule is this? Surely the best guarantee I can have that the fog is fog is if I fail to see the sign saying 'fog' because of the fog."

James Fenton (ed.) The Original Michael Frayn (Edinburgh: Salamander Press, 1983) p. 67.