Forum:KB:Music - Imperial motif

Music question relating to John Williams's 1977 score for ANH. There is a theme sometimes known as "Imperial motif". The article links to this music extract. Other sources I have read consider the Imperial motif to be a theme for Darth Vader (NB. this music was written before Imperial March so we're only concerned with the first film here).

However there is another quieter theme which is sometimes considered to be an Imperial motif and also a Darth Vader motif. You can hear it in Ep IV in several places, notably when Leia is marched before Vader on the Tantive IV, just after R2 & 3PO escape in the life pod. It has low triplets on woodwind over cello arpeggios. I am unable to upload an OGG file as I'm not a trusted editor but here is a musical score. On the soundtrack you can hear it in "Imperial Attack" from 04:55.

Is there any more source material/book which can confirm this as a Darth Vader theme? Realy would be interested to know.