ARTIST: David Gilmour
GENRE: Rock, Art Rock, Blues Rock
CONCEPTS: Target notes, pentatonic scales, melodic phrasing, ballad soloing
SOURCE: Creative Guitar Studio
TOPIC: David Gilmour Scale Concepts

The approach used by David Gilmour for the bulk of his scale ideas, is largely based upon the Blues scale and Minor Pentatonic, with a lot of reference to the Major 2nd degree from the Dorian mode. 
It's quick to hear on many of his solos, such as the one he plays in the Pink Floyd song, "Yet Another Movie." That solo is largely pentatonic thrashing for the most part, but it's also full of feeling. 
And, when we analyze the way he uses the; Blues, his bends and the obvious strong connection he has toward players like; Clapton, Jeff Beck and the Muddy Waters & John Lee Hooker sound... 
we end up with an instantly recognizable tone only associated to the David Gilmour style.