Frozen Thames

Source BBC "'between 1309 and 1814, the Thames froze at least 23 times and on five of these occasions -1683-4, 1716, 1739-40, 1789 and 1814 - the ice was thick enough to hold a fair."

When the Thames froze over
It was not a common event
It might slow commerce
So cold as to cause frost damage
But on the rare times it froze
People gathered a fair upon the ice
Both to defy winter
And to celebrate in hard times