The phrase to miss the bus, or the boat, etc., means to be too slow to take advantage of an opportunity.

In A Concise Dictionary of Phrase and Fable (1993), B. A. Phythian explained:

This expression is said to originate in an Oxford story of the 1840s about John Henry Newman, fellow of Oriel College, vicar of the University Church and one of the foremost theologians of his time. Newman’s decision to join the Roman Catholic Church—in which he later became a Cardinal—was an event of great importance in its day. One of his Oxford adherents, Mark Pattison, set off to talk to him at the time this fateful decision was being made, but missed the bus and therefore also missed a conversation that may have taken him to Rome. Unkind commentators suggested that Pattison’s mishap was in fact a serious failure of nerve, and this gossip gave jocular notoriety to his excuse that he had merely missed the bus.

Mark Pattison (1813-84) was an English author and Church of England priest. The earliest mention of the incident is found in Critical Miscellanies (volume 3, London, 1886), by the British journalist, author and politician John Morley (1838-1923):

When the great secession came in 1845 Pattison somehow held back and was saved for a further development. Though he appeared to all intents and purposes as much a Catholic at heart as Newman or any of them, it was probably his constitutional incapacity for heroic and decisive courses that made him, according to the Oxford legend, miss the omnibus.

In this text, “the great secession” refers to John Henry Newman (1801-90), joined by some of his followers, leaving the Church of England and his teaching post at Oxford University and being received into the Catholic Church.

On Thursday 4^th April 1940, the British Conservative statesman Neville Chamberlain (1869-1940), then Prime Minister, declared:

One thing is certain: Hitler missed the bus.
When the war broke out German preparations were far ahead of our own, and it was natural then to expect that the enemy would take advantage of his initial superiority to make an endeavour to overwhelm us and France before we had time to make good our deficiencies.
Is it not an extraordinary thing that no such attempt was made? Those seven months that we have had have enabled us to make good and remove our weaknesses; to consolidate and to tune up every arm, offensive and defensive, and so enormously to add to our fighting strength that we can face the future with a calm and steady mind whatever it brings.

The following is from the Manchester Evening News (Lancashire) of Saturday 26^th October 1940:

JAPAN HAS “MISSED THE OIL BUS”

Despite reports that Japan has concluded an agreement under which she will obtain a large percentage of her oil requirements in the Dutch East Indies over the next six months, New York oil experts in close contact with Far Eastern affairs maintain Japan has “missed the bus” in the Dutch colony.
If Japan had attacked on May 10—the day Hitler invaded Holland—a Japanese conquest would have been a certainty. But, the experts say, the day of opportunity for quick conquest of the Indies, rich in oil, tin, and rubber, has now passed.