We can actually see an excellent example of ironic figurative language being used to create comic effect in the very first paragraph. He opens the story by describing the morning sun shining on the setting and the characters; however, he describes the sunshine in such a way as to liken it to rainfall, as we see in the phrase, "The morning sunshine descended like an amber shower-bath on Blandings Castle," and using the word "like" to describe one thing by comparing it to another is of course a simile. But what's very interesting about the simile that makes it ironic, meaning contrary to what one would expect, is that sunshine is not typically likened to rainfall as they are actually exact opposites. He continues to create comic effect using this simile by describing every person and object that the sunshine lit up as if the sunshine was falling upon them, just like rainfall, just as if they were displeased by the "sunshine fall" in the same way that they would be displeased by becoming wet due to rainfall. We especially see this comic effect in the lines:
It fell on the baggy trousers-set of Angus MacAllister, head-gardener to the ninth Earl of Emsworth ... It fell on the white flannels of Hon ... It also fell on Lord Emsworth himself and on Beach, his faithful butler.
Hence, this description of all of the people that the sunshine has so unexpectedly fallen upon creates a comic effect because it is certainly an ironic description.
Further comic irony can be seen in Wodehouses description of the event concerning the telescope at the beginning of the story, particularly the moment the cow comes into play. We are told that Lord Emsworth purchased a telescope immediately after reading an article on astronomy, and, in the beginning of the story, he is giving the telescope a test run. However, what's very funny and ironic in the sense that it is different from what would be expected is that the first thing he looks at through the telescope is a cow. Lord Emsworth continues to look at the cow, while we would expect him to be looking at things more astronomically related, until he gets bored of the cow, or as the author more comically phrases it:
It was a fine cow, as cows go, but like so many cows, it lacked sustained dramatic interest. Surfeited after a while by the spectacle of it chewing cud and staring glassily at nothing, Lord Emsworth decided to swivel the apparatus ....
In this passage, the phrase "sustained dramatic interest" is certainly a comic way to describe the cow as it contrasts greatly with what cows are and do. Something that creates "sustained dramatic interest" would likely be more active, like a wildcat roaming through the estate's park, and just like the author describes, the cow is chewing cud and "staring glassily at nothing." Hence the descriptive phrase of the cow creates comedy by being a very true, ironic contrast with the cow. In addition, even the descriptive phrase "staring glassily at nothing" creates a comic effect by simply describing what's perfectly true about cows.
Hence, we see that a great deal of comedy can be seen all throughout the story in many different forms.