The "circus" stuff is because this is from a 1968 concert film called "The Rolling Stones Rock and Roll Circus", with a bunch of bands that were friends with the Stones, like The Who, Jethro Tull (with Tony Iommi, who went on to found Black Sabbath on guitar!), Taj Mahal, etc.
Also, a "Girl Guide" is the British equivalent of the Girl Scouts in the U.S. - presumably of high school age in this song, and the "we" of the "we'll soon be home" is the girl guide's man and his horse.
That lyric is NOT "Jerrold, Jerrold, Jerrold," it's "'cello, 'cello, 'cello." They wanted a cello there when they recorded it in the studio, but couldn't afford one, so they used the sound of the word to fill in the space and it became standard during their live sets.
Pete Townshend saw the Rolling Stones doing a soundcheck once and saw Keith Richards doing the windmill move with his arm and thought he played guitar like that. It turns out Keith was just limbering up and Pete mistook it for a playing technique. It became his signature from then on.
This is the composer’s (guitarist Pete Townshend) early attempts at writing a long form piece (the term now known as rock opera). One of the band’s mangers at the time was the son of classical conductor and quire familiar with classical music and opera. Pete was becoming less interested in composing standard pop tunes and didn’t know how to write a seven minute song that told a singular story. That band manager (Kit Lambert) told Pete that if he couldn’t write a seven minute song just write a few songs that were 2:50 in length and stitch them together. That’s how this particular song came to be….
