For some reason I thought I'd read Bill Owen had written the play, but in looking back at my sources I see that Clarke created the original stage treatment it was based on after all. :-[
At any rate, it ran for a few summer seasons in the mid-80s with Bill Owen, Peter Sallis, and Jane Freeman participating (though I think Owen was the only one who appeared in all stagings) and that is where Pearl, Howard, Marina, and Crusher came from. The actors playing it the final season were the ones they took to the TV series after Clarke and Bell came to see the play and were impressed by their performances.