Here's confirmation of my account above, from a book review section in the Guardian last December.
"While he is talking, Archer's manner fluctuates between aggrieved headmaster and naughty schoolboy, and his face never seems absolutely sure which side of the detention desk it is supposed to be on. Oddly, the image that stayed with me long after I finished Crick's book was of Archer playing Puck at Dover College, where he taught PE. He gained his entrance to the stage by leaping over a hedge from a platform or a trampoline. It has often seemed as though he has since perfected this two-footed entrée into most areas of his life. 'I was a wicked Puck,' he agrees now, 'dancing about, kicking everyone, jumping over them, causing trouble ... it was an ideal part for me.' Archer likes to think of himself as mischievous, surprising. With all his teasing and game playing, does he, I wonder, ever fear he might lose sight of who Jeffrey Archer really is?"
There was, unfortunately, no picture, and this is accurate as to personal history (though the play was performed in Kearsney Abbey grounds by the Dover Players. It is possible that the report I saw which was wrong was wrong because of the reporter, not the source.