Song 46 (set to "Peace, perfect peace" in many hymnbooks) is one of the Orlando Gibbons hymntunes. This Air is found in the excellent OUP series "Oxford Hymn Settings for Organists".
The first section features the tune on an 8' flute in the pedal under contrasting solo registers. For the second section, the tune moves to the middle voice (Gt 8' flute and 4' principal I think); the upper voice is Sw flutes to quint. Both these sections are trios in a neo-Renaissance style. The final section is on Sw celeste, finishing with more than a hint of an English cadence