[link to original on tumblr]
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In the meantime, I learned the bass part. This isn't the complete song, but the sections are repeated, and there's at least one of each here. I learned the guitar chords too, but the first verse has some kind of effect (I think echo) that I don't have a good way of producing, and I haven't figured out the right rhythm for the rest.
In learning the parts and playing along, I found two things that demonstrate the titular wishing, or - more specifically - the lack of fulfillment that's related to it. There's a grammatical error in the bridge: "I wish that everything was gold" instead of "I wish that everything were gold" (because subjunctive verb forms are weird). So there's an imperfection there, which is similar to the lack of fulfillment the speaker/singer has because he's away from his "little darling." (I don't know if Jeff Lynne intended that line to have an error or not, but the point stands either way. I will say though that "I wish that everything was gold" sounds better when sung than "I wish that everything were gold," even if it is grammatically incorrect.)
While the song is in A major, the verses and bridges end with a G note in the bass, which doesn't provide a resolution, and - furthermore - is an accidental. So there's a musical sense of that yearning. In the verses and the bridges, the lyrics above that non-resolving, accidental G note are "I'm wishin'," which seems to emphasize that feeling even further.