English courts will sometimes read into a contract a term that nobody wrote down. In The Moorcock, in 1889, Lord Justice Bowen said the aim is “to give such business efficacy to the transaction as must have been intended at all events by both parties.”
In 1939, in Shirlaw v Southern Foundries, Lord Justice MacKinnon described such a term as “something so obvious that it goes without saying.” If an officious bystander suggested writing it into the agreement, the parties “would testily suppress him with a common ‘Oh, of course!'”