Paul, that would have been a proper good old fashioned 4lb hook length and correct me if I'm wrong but proper salmon hooks? Not sure what weight rod he's using but you can't help admire how he puts a line out.Have a look at this clip of Lee and Joan Wulff and the tackle they're using, move to 8 min 20sec, Lee Wulff is using a 6ft rod and a 4lb point. Now it's not the Spey in spate but it demonstrates that light tackle has its place . . .
So much for the tippet determining the fly size