How to Play the Riff from Breadfan by Budgie

This is an awesome riff from Welsh proto-metallers Budgie. It's nowhere near as well-known as it should be, but for me it's right up there with the greatest rock riffs of all time.

There's nothing too complex going on here; all the notes are taken from the A minor pentatonic scale. I found the biggest challenge was deciding on the best right-hand picking pattern. Because of the interesting way the notes are grouped rhythmically there's no one obvious way to do it, but I settled on a method that seems to let the riff flow naturally whilst maintaining the aggressive accents in the right places. 

I've written out the main riff below, together with the verse riff. As I say in the video, I might get round to looking at some of the other riffs in the song at some point in the future if enough people are interested. Download the tab here if you want.