What a coincidence! I listened to this yesterday for the first time in ages.
The orchestra was arranged to glue together the songs recorded by the band. If I'm not mistaken, the album was originally recorded as a sort of demo for Decca's new "stereo" recording technique. Obviously, there is a HUGE difference in quality between the Mellotron and the full orchestra. But "Knights" is definitely a great mix. "Tuesday Afternoon" is my fav from the album. I need to listen to this record in it's entirety. Like "Dark Side of the Moon. For me, this was the first solid concept album. Sgt. Pepper had a concept, but was more of a concept in order to bring a hodge podge of different tunes under a single conceptual umbrella.
I noticed in the overture (The Day Begins) a solo flute line the really jumped out, so they were using some spot mics in addition to the "Decca tree".
Funny story about "Knights" being a "breakout" hit in Seattle. Seems the DJ on the graveyard shift between 12 and 4am needed a long song so he could go smoke his bong... He unknowingly created a hit!