The Clerk's Tale and the expectation of astonishment

Penelope Fitzgerald mentions this as one of the stories that developed her love of plots with a twist at the end. But it appeared on the 1970 A-level exam with this question: 'Whatever its other merits, The Clerk's Tale does not achieve its effects primarily through surprise.' So is it a plot with a twist or not?

Here's the story. Walter the Marquis marr…