Streetly Electronics Mellotron Tape Library
A gently plucked guitar acoustic sound best suited to Fast Keyboard Runs designed to impress the ladies. Of course looking like Antonio Banderas might also help a little. Mind you, it might have cheered up Desperado a bit if they all carried Mellotrons instead of guitars, don't you think?
Incidentally - you may have been led here by the reference on the Wikipedia page that deal with the Beatles song 'Bungalow Bill'. Whoever wrote the sentence 'the song opens with a flamenco guitar solo (taken from a seldom-heard Mellotron bank of Spanish guitar runs)' doesn't know what they are talking about. The whole phrase from the intro to 'Bungalow Bill' came from one note played on the Mellotron which played back the whole sequence, kind of like a sound effect. It isn't 'played' on the Mellotron at all. The sample you hear below was played (by me) and is maybe as fast as you can play the instrument without resorting to weird tactics.