Sweet Lady

Composer: Brian May
Meter: 3/4, 4/4 (Bridge)
Key: E-Major
Form:

      Intro (AAAA)|  Verse | A  | Chorus |
                  |  Verse |      Chorus |
             | AA | Bridge | BB | Chorus | Solo (chorus) - Outro solo |

"Sweet Lady" is arrangements-wise the only true hard rock number on the album. For this reason its presence is very important since Queen was supposedly a hard rock band. Still it gets often criticized by the lyrics especially the "...cheese" line. Music-wise there's nothing to be criticized.
The form simplified written is I-ABABCB(B)-O. Many section transitions are executed through instrumental connectors in a relatively irregualar way.
The key is the guitarfriendly E-Major without any hint of modulation. The harmony uses relatively few - six chords: I, IV, V, vi, bVI and bVII.

Intro
The instrumental 16 measure intro consists of four variant phrases each using the double-plagal cadence. We have three rhythm guitars in the mix, one of which is joining in m.4. along with the bass and drums. The proper back-beat of the song establishes for the fourth phrase.
 

| E (sus4) | D(sus4) | A(sus4) | E1...  |
| I        | bVII    | IV      | 1st    |

| E (sus4) | D(sus4) | A(sus4) | E1...  |
| I        | bVII    | IV      | 1st    |

| E (sus4) | D(sus4) | A(sus4) | E      |
| I        | bVII    | IV      | 1st    |

| E (sus4) | D(sus4) | A(sus4) | E      |
| I        | bVII    | IV      | 1st    |

Verse
The 20 measure Verse has some phrases of uneven length: 4+4+3+5+3 AA'A"BC where A" is the ending of the A'. Note the last four measure is backed with the main-hook guitar riff but this time the lead vocal phrases don't follow it slavishly.

/------------ 2x---------------\\
| E    | A     | B A   | E     |
| I    | IV    | V IV  | I     |

| A    | B A   | E     |
| IV   | V IV  | I     |

| B    | -     | C#m   | A     | E     |
| V    | -     | vi    | IV    | I     |

| D(sus4) | A(sus4) | E     |
| bVII    | IV      | I     |

The last instrumental connector in contrast with the previous ones can be derived from the verse's harmony between m.5-12. The two phrases are overlapped resulting in uneven (7) phrase length.

| E    | A     | B A   |
| I    | IV    | V IV  |

| E    | A     | B A   | A    |
| I    | IV    | V IV  | IV   |

Chorus
The chorus is 10 measure long and has four phrases: 2+2+2+4, AAAB. The arrangement is added multitrack guitar harmonies with many chromatic motions. The rhythm guitars play mostly pentatonic figures.

/----- 3x-----\\
| E7   | A    |
| I    | IV   |

| C    | A    | E    | -    |
| bVI  | IV   | I    | -    |

The lead melody is antiphonal arranged between solo and harmony vocals. In the last chorus most of the solo vocals are omiitted.

Bridge
This bridge is a relatively usual "middle-eight", except it changes the meter to 4/4. The latter helps to create the bridge-esque contrast with the rest of the song along with the harmony that is open at both end. The 3/4 meter returns for the last measure.

| B    | D   A  | E    | -    |
| V    |bVII IV | I    | -    | 

                          3/4
| B    | C#m D  | A D/A  | -    |
| V    | vi bVII| IV bVII| -    |

The phrases start with harmonized vocals, and the section closes with in a very Queen-esque bent vocal harmony.

Outro
The outro starts as an instrumental chorus. The backbeat is gradually turning to a proto-punk double-time feel. The rythm guitar departures from the original riff from the third phrase on.

/---- 3x ----\\
| E7  | A    |
| I   | IV   |

| C   | A    | E    | A    |
| bVI | IV   | I    | IV   |

After the instrumental chorus harmony-wise we have yet another chorus, but this time without the guitar harmonies. The rhythm guitars change to bluesy 5-6-7-6 figures, bass switches to boogee-woogee mode until the end of the song.

/---- 3x ----\\
| E7  | A    |
| I   | IV   |

| C   | A    |
| bVI | IV   |

From here on the harmony is vamping between the tonic and subdominant chords fading gradually out.

/---- 16x ----\\
| E    | A    |
| I    | IV   |

Beside the lead guitar there are some additional guitars playing repetitive chromatic and triadic (these ones in triplets) and pentatonic motifs.