Among the surprise celebrities making appearances during previews (since March 7) were Roger Moore, Liam Neeson, Zoe Caldwell and Nathan Lane. Most put in runs of two or three nights in a row, and Moore, who showed up at the first performance, recently returned to the Lyceum.

Oscar winner Kevin Kline, who began performances Friday as the mystery guest, will do opening night duties.

The Play What I Wrote, a quirky London theatrical sensation, is directed by Kenneth Branagh, and features actors McColl and Foley and Toby Jones on stage. It was written by McColl, Foley and Eddie Braben. The 2002 Olivier Award-winning play — an homage to the famed-in-Britain-but-mostly-unknown-in-the-U.S. comedy team of Ernie Wise and Eric Morecambe — "revolves around Hamish, who no longer wants to be part of his comedy double act with Sean," according to production notes. "Instead, he wants to see the play he has written, A Tight Squeeze for the Scarlet Pimple, properly mounted on the Broadway stage. But before this can happen, he needs a major star to play the supporting role to his lead role." Hence, the surprise appearances by various bold-faced types.

The show is becoming a forum for many a Broadway return. The Play What I Wrote marks Zoe Caldwell's first Broadway appearance since Master Class in the mid-90s, and Nathan Lane's first Broadway credit since leaving The Producers.

The Lyceum is at 149 W. 45th Street. For ticket information, call (212) 239-6200.