In this instance the departure is radical: this is a real car crash of a ballad, impacted (the beginning and end have crushed together) and distorted, yet still recognizable.

[…] rocky pinnacles, from whence he sends forth a sort of choking chattering song, if such it can be called, or, with an upjerk of the tail, hops away with a loud musical whistle, very much after the manner of the Blackbird.

I mean there were the little things like the B-double that was allowed in the town and actually allowed to park in the street until it was ready to leave on its next trip. Not only is this illegal but a B-double is not allowed to leave the designated route at any time.

I can conduct you, lady, to a low / But loyal cottage, where you may be safe.