Thanks Jeff, I'll leave the end stop loose as you recommend, and take my cordless driver with me. I am going to get the router out and make the Rolls Royce of all thwart boards, perhaps veneer it with rare tropical hardwoods!
I think the boards went because, as Accony suggested, no one put the money in the box, and the Pitsford boards were getting rather spintered. I would have thought AW could hire boat seats out, if they were a little more enterprising.
Sorry you can't get a board in your sports job Charlie, there's a downside to everything!