Looks like Derek Daly though… since it seems to say that on the side. Derek Daly was active in 78, which is when I assume that photo is. Here’s the same picture of Derek Daly at Long Beach, without the crop..
http://b.f1-facts.com/ul/a/3533
Evidence is strong! ;) I vote Daly.
( otherwise : Rupert Keegan? )