Remember the guitar lick In Sultans of Swing following “and Harry doesn’t mind..” ?
In songbooks or tabs you will find something like:
(play b-string at fret 8, plus g-string at 7th fret, bend g-string one whole note, notes g and d, the d is bent to e)
In fact this is the way Knopfler seems to play it on many old or new live recordings.
I suspect that on the studio versions (both the CD version and the alternative vinyl single version that was released in some countries like Germany or England), he played it differently, like this:
(b-string at fret 6, g-string at fret 7, then bend up *both strings* one whole note, use the second and third finger of the left hand for bending, notes f and d, bent to g and e)
This is more difficult which might be an explanation why is was only played in the studio this way. The problem is you must be very careful not to mute the b-string accidentally with the finger that bends the g-string.
If you play it this way, you can make it scream more, also you can release the bend and both notes will perfectly match the following Dm chord (listen carefully, this was what gave me the idea to this).
The same bend seems to appear on ‘Once Upon A Time in the west’: oy yeah … (the bend, and release it) …. once upon a time in the west”
See this article for one of my youtube videos where I also demonstrate this bend.