The Thames, unmindful of the foolish crowds upon its banks, flowed on quietly as of yore.

From Charles Mackay's Extraordinary Popular Delusions and the Madness of Crowds:

An instance of the faith in predictions occurred in London in the year 1524. The city swarmed at that time with fortune-tellers and astrologers, who were consulted daily by people of every class in society on the streets of futurity. As early as the month of June 1523, several of them concurred in prediction that, on the 1st day of February 1524, the waters of the Thames would swell to such a height as to overflow the whole city of London, and wash away ten thousand houses. The prophecy met implicit belief. It was reiterated with the utmost confidence month after month, until so much alarm was excited that many families packed up their goods, and removed into Kent and Essex. As the time drew nigh, the number of these emigrants increased. In January, droves of workmen might be seen, followed by their wives and children, trudging on foot to the villages within fifteen or twenty miles, to await the catastrophe. People of a higher class were also to be seen in wagons and other vehicles bound on a similar errand. By the middle of January, at least twenty thousand persons had quitted the doomed city, leaving nothing but the bare walls of the homes to be swept away by the impending floods. Many of the richer sorts took up their abode on the heights of Highgate, Hamstead, and Balckheath; and some erected tents as far away as Waltham Abbey on the north. Bolton, the prior of St Bartholomew's was so alarmed, that he erected, at a very great expense, a sort of fortress at Harrow-on-the-Hill, which he stocked with provisions for two months. On the 24th of January, a week before the awful day which was to see the destruction of London, he removed thither, with the brethren and officers of the priory and his entire household. A number of boats were conveyed in wagons to his fortress, furnished abundantly with expert rowers, in case the flood, reaching so high as Harrow, should force them to go further north for a resting place. Many wealthy citizens prayed to share his retreat; but the prior, with a prudent forethought, admitted only his personal friends, and those who brought stores of eatables for the blockade.

At last the morn, big with the fate of London, appeared in the east. The wondering crowds were astir at an early hour to watch the rising waters. The inundation, it was predicted, would be gradual, not sudden; so that they expected to have plenty of time to escape as soon as the saw the bosom of the Thames heave beyond the usual mark. But the majority were too much alarmed to trust to this, and thought themselves safer ten or twenty miles off. The Thames, unmindful of the foolish crowds upon its banks, flowed on quietly as of yore. The tide ebbed at its usual hour, flowed to its usual height, and then ebbed again, just as if twenty astrologers had not pledged their words to the contrary. Blank were their faces as evening approached and as blank grew the faces of the citizens think that they had made such fools of themselves. At last night set in, and the obstinate river would not loft its waters to sweep away even one house out of then thousand. Still, however, the people were afraid to go to sleep. Many hundreds remained up till dawn of the next day, lest the deluge should come upon them like a thief in the night.

On the morrow, it was seriously discussed whether it would not be advisable to duck the false prophets in the river. Luckily for them, they thought of an expedient which allayed the popular fury. They asserted that, by an error (a very slight one) of a little figure, they had fixed the date of this awful inundation a whole century too early. The stars were right after all, and they erring mortals, were wrong. The present generation of people was safe, and London would be washed away, not in 1524, but in 1624. At this announcement, Bolton, the prior dismantled his fortress, and the weary emigrants came back.