Here's a link to another shot from that BB King session (with Klaus Voormann at left). Peter's guitar has a tailpiece so I'd guess it's not his earlier guitar.
http://www.gettyimages.com/detail/ne...photo/94103347
In contrast, here are a couple of shots of Peter at the 8/25/70 benefit show at the 100 Club in London, also with Duster Bennett:
Anyone know who the sax player is? Wondering whether it might be John Altman from the Brunning Sunflower Blues Band.