I BELIEVE IN FATHER CHRISTMAS (Emerson, Lake & Palmer)

Written by Greg Lake and Pete Sinfield in the key of D in 4/4 time
Released on the album: Works Volume 2 (1977)
Released as a single in 1975
I Believe In Father Christmas on Wikipedia | Lyrics
Fingerstyle version for single acoustic guitar in Drop D tuning

thumb: x             Hammer on: h             Bend up: V                   Play or don't: ()
index: a             Pull off: p              Bend down: Λ                 Break: b
dirty: b             Slide up: /              Fret but don't pick: !       Downward stroke: ↑
ring: c              Slide down: \            Staccato: :                  Upward stroke: ↓
pinky: d             Arpeggio: ~~~            Mute: m

Red colored exclamation marks offer additional fretting information

The intro resembles the intro of John Lennon's "Dear Prudence", which might have been the driving force behind
Greg is hybrid-picking this song
For fingestyle, I suggest the following picking patterns: ac - x - ac - x
                                                          xc - a - xc - a
INTRO

e---10a---------12dp10a---------\---!9c--------10dp9c---------\---|  picking pattern:
b-----------------------------------------------------------------|  ac - x - ac - x  (2x)
g---11b---------11b-------------\----9b--------9b-------------\---|
D----------0---------------0---------------0-------------0--------|
A-----------------------------------------------------------------|
D-----------------------------------------------------------------|

e--!7c--------9dp7c---------\----5a---------7dp5a---------\---|  picking pattern:
b-------------------------------------------------------------|  ac - x - ac - x  (2x)
g---7b--------7b------------\----6b---------6b------------\---|
D---------0------------0----------------0------------0--------|
A-------------------------------------------------------------|
D-------------------------------------------------------------|

e---3a---------\----5dp3a----------\----2c--------3dp2c----------|  picking pattern:
b----------------------------------------------------------------|  ac - x - ac - x  (2x)
g---4b---------\----4b-------------\----2b--------2b-------------|
D---------0-------------------0---------------0-------------0----|
A----------------------------------------------------------------|
D----------------------------------------------------------------|

e---0---------0---------0----------2c------------|  picking pattern:
b------------------------------------------------|  ac - x - ac - x  (2x)
g---2b--------0---------2b---------2b--------/---|
D--------0---------0----------0---------0--------|
A------------------------------------------------|
E------------------------------------------------|

e---3a----------5dp3a----------------2c--------3dp2c---------|---0---------0---------2cp0-----------------|  picking pattern:
b------------------------------------------------------------|--------------------------------------------|  ac - x - ac - x  (3x)
g---4b----------4b--------------\----2b--------2b------------|---0---------2b--------2b---------------/---|  ac - x - x
D----------0---------------0---------------0-------------0---|--------0---------0------------0------------|
A------------------------------------------------------------|--------------------------------------------|
D------------------------------------------------------------|------------------------------------0-------|
                                                                                                  ¼  
e---3a----------5dp3a----------------2c--------3dp2c---------|---0---------0---------2bp0--------------|  picking pattern:
b------------------------------------------------------------|-----------------------------------------|  ac - x - ac - x  (3x)
g---4b----------4b--------------\----2b--------2b------------|---0---------2b--------2b----------------|  ac - x - x
D----------0---------------0---------------0-------------0---|--------0---------0------------0---------|
A------------------------------------------------------------|-----------------------------------------|
D------------------------------------------------------------|------------------------------------0----|
                                                                                                  ¼
e---2bp0-----------|---2bp0-----------|---2bp0-----------|  picking pattern:
b------------------|------------------|------------------|  ac - x - x (3x)
g---2b-------------|---2b-------------|---2b-------------|
D---------0--------|---------0--------|---------0--------|
A------------------|------------------|------------------|
D-------------0----|-------------0----|-------------0----|  info
              ¼                 ¼                 ¼
1ST VERSE
... to be continued
e-----------------------|-----------------------|  picking pattern:
b-----------------------|-----------------------|
g-----------------------|-----------------------|
D-----------------------|-----------------------|
A-----------------------|-----------------------|
D-----------------------|-----------------------|

There are two versions of the song, an inflated orchestral version and a less pompous one without orchestra. Maybe I work out the rest of it one day, if I find a cute tab solution for the interlude, which in fact is based on Prokofiev's "Troika" from the suite "Lieutenant Kijé". This was one of Emerson's “glorious ideas“.
Or I use something totally different, as in "The Sage".