King Crimson - Starless - orig from Red Album

Possibly my favorite song of all time.

great track.

Those strings sure sound like a Mellotron.
Because of the way they worked, languid pads were what was played 99% of the time.
Boy, those things were touchy! Having the moving head rack across the tape strips were easy to throw out of alignment. Never had one, but I played a couple. Knew a guy (banker's kid) that one as far back as this song.
And that flute like figure is a Moog or an ARP, but I'm going with the former. ARPs got a little mushy when playing a subdued, clamped-down tone.

There's portamento on it, and Mellotron couldn't do that.
Because it's the same amount & ramp rate on every note, it's hard to believe it's a wind instrument.
That's why I thought it is a synthesizer.

term..

The sound you're hearing is likely Fripp's sustaining guitar.

There is no Moog, mini or otherwise, or AARP with this line up of KC.

There is some violin, trumpet and cello on the album in places.

As someone who plays both keys & guitar, what I'm hearing can't be done on guitar, or at least couldn't in the early 70s. As great as Fripp is at coaxing sounds out of a guitar, I'm not hearing guitar.
I'm not big into hypertech guitar, and i don't have the hardware to do it, but a digital pitch shifter would do it, if i had one. But, those didn't exist 45+ years ago.
Whether it's listed or not, it still could be a producer, or a pal of the band doing synthesizer work.
Still convinced it's a Moog.

The whole string intro features it. It has a woodwind-ish tone, but the filter is clamped down.
I'm convinced it's a synthesizer because there's portamento on it. That's the effect of the pitch starting just below the destination and drifting into pitch. It's subtle, but it's there.

Are you familiar with all of the timber and textures that Fripp's affected guitar can make?

Personnel

King Crimson

Robert Fripp – electric guitar (all tracks), acoustic guitar (2), Mellotron (2, 4, 5), Hohner pianet (5)
John Wetton – bass (all tracks), vocals (2, 3, 5)
Bill Bruford (credited as William Bruford)[39] – drums (all tracks), percussion (3–5)

Additional personnel

David Cross – violin (4, bonus tracks), Mellotron and electric piano (bonus tracks)
Mel Collins – soprano saxophone (5)
Ian McDonald – alto saxophone (3, 5)
Mark Charig – cornet (2)
Robin Miller – oboe (2)
Julian Lloyd Webber[40] (uncredited) – cello (1, 2, 5),[7]
uncredited – double bass (5)[7]

...that it's the oboe, with harsh EQing.
It's still the portamento that bugs me. I can see a reed player bending up, but a double reed instrument exactly the same on every note seems hard to believe.
In the long run, it doesn't matter. It's cool song by a great band. I will admit I'm a bigger fan of the Belew/Levin period of the band.