The willow pattern, as we know it today, was designed by one Thomas Minton about 1780, and brought from him by Thomas Turner, a famous potter and manager of Shropshire pottery.
Here is the story:
Knoon-shee, a lovely Chinese maiden, whose affections were bestowed upon her father's secretary, Chang, but who was commanded by her parents to wed a wealthy rival suitor.
She refused to comply with their wishes, whereupon her enraged father locked her up in the little house just visible on the left of the temple. From here she contrived to send a message to her lover, 'Gather thy blossom, ere it be stolen.' Thus encouraged, Chang succeeded in entering the apple orchard and carrying off his beloved. So we see them hurrying over the bridge. Knoon-shee with a distaff, and Chang carrying her box of jewels, while the angry father follows hard after them armed with a whip - in some patterns also accompanied by the discarded lover.
The couple made good their escape in the 'Chinese ship sailing by' and landed on the island, which can be seen on the left of the picture, where they took refuge in the little wooden house. But the father and discarded suitor tracked them and set fire to the house while they were sleeping; and so the lovers perished.
Next morning, from the ashes rose their spirits, in the forms of two doves. And so we see them with out-stretched wings flying off to the realms of eternal happiness.
http://www.spode.co.uk/history/history_pattern.html