I would add that making ignorance of the law a valid excuse would be a logistical farce. Mens rea is a real thing that’s examined during a criminal trial. The defendant’s state of mind can absolutely factor into their sentence or even whether they’re convicted at all; “ignorance of the law is not an excuse”, ignorantia juris non excusat, even has some exceptions under US law. But you could not possibly for every crime burden the prosecution with proving that the defendant 1) committed the act 2) intended to commit the act, and now 3) knew the act they were committing was a crime. Mens rea, while necessary in a fair system, is hard enough; condition (3) would make it functionally impossible to convict anyone who didn’t a) explicitly refer to what they were doing as a crime, b) receive a formal education in the relevant area of law, or c) commit a crime literally everyone is expected to know like murder or armed robbery.
“London’s smallest statue” doesn’t seem feasible to track without other qualifiers.