What song is Bill Bailey parodying in this clip from "Part troll"?

Can somebody tell me what song, or even band Bill Bailey is parodying in this short clip from his “Part troll” dvd?

This clip is right before his “love song” bit, and right after he mentions needing “the proper orchestral backing of this magnificent device here”.

Here’s a clip of the bit I’m talking about: http://www.mediafire.com/download/lo60zj0dg0rg7d7/unknown_ballad_tune.flac .
note for mods: clip is only 30 seconds long

Stairway to Heaven. It’s not so much a parody as a direct quote.

Bill Bailey also makes the joke about how The Edge is really just playing basic twangs, and his entire schtick is that Effects Pedal.

Then this video turned up.

And he’s a billionaire. sigh