I don't know exactly the date of the pic, but there's a clue:
Mark's guitar neck
both of his Fender strats didn't have any 'skunk stripe' at the back of the neck, sot it can't be in 79 (unless Mark would have borrowed a guitar to JJ ?)
it rather looks like a Schecter one piece maple neck with bird eyes at the back of the headstock.
so it must be during the 80's
If it was in 88, I guess Mark would have used the pensa which don't have any skunk stripe'.
Regarding Mark's clothes, he used to wear such "without T"-shirts during BIA tour (e.g. wembley).
So to me, 1985 fit well.