With a bit of Sunday research and digging out of old copies of Jazz Journal a few snippets about Hank and the NorthSea Fest have come to light.
He was due to appear in 1978 as part of an all-star sax feature with Illinois Jacquet, Eddie Lockjaw Davis, Archie Shepp, Stan Getz, David Newman and youg wippersnapper David Murray but apparently didn't make it. Extract of festival report below - sounds like a shambles:
The very late planned appearance I was thinking of was planned for 1986, even later than I thought, and it looks as if Hank was listed almost as an afterthought with Rein de Graaff's group with Dave Pike as part of a Charlie Parker tribute (see bottom left 'Bird Winners 1986'). You almost need a magnifying glass to even notice that he was billed. Extremely sad, as I think Hank finally passed away in late May of that year.
On a more positive note, what an astonishing lineup NorthSea featured that year !