Gershwin's most famous tune, here arranged in a version which went quite a distance from the original. Summertime, initially an aria of the Porgy and Bess musical, is considered the most covered song in history. Wikipedia states that there are more than 33.000 versions of it, (who counted that?) - of course not including this one.
There is also a nice website exclusively dedicated to cover versions of this fantastic song: http://thesongsummertime.wordpress.com
This version initially evolved during the famous “Porto Covo Campfire Sessions” in the early 80s, but to my knowledge nobody ever wrote it down. The chord progression is somewhat different from the original. Main feature of this arrangement is its simplicity. Starting with a plain Am chord and sliding an Am7 two frets up is the figure of the first four bars, and repeated later. The rest is Dm with a descending bass, F and E, and that's it. And my favourite chord Am6 at the end. Lightly bouncing triplet rhythm throughout.