It's nostalgia time, the end of an era. Stephen Sondheim's Merrily We Roll Along is the last Watermill musical to be directed by John Doyle. The era began ten years ago when the theatre's visionary director Jill Fraser phoned Doyle out of the blue, and asked if he'd be interested in directing Cabaret. Doyle jumped at the opportunity - he was out of work at the time. Neither Fraser nor Doyle can have imagined that their new artistic collaboration would one day lead to Doyle's Watermill production of Sweeney Todd being transferred to the West End, and then Broadway.

Jill Fraser planned Merrily as her last Watermill production before retirement, but she didn't live to see it - she died of cancer two years ago. The choice has turned out to be almost eerily appropriate, for Merrily is a musical about looking backwards. Liz Ascroft's spare set design features an old-fashioned tape recorder, whose reels spin backwards - truly rewinding time, for there were no quick-fire digital searches in those tape recording days. The show itself begins in the mid-1970s, and ends in 1957.

Sondheim first introduces us to Mary and Gussie in 1976. Mary is a cynical theatre critic: "I just figured out what the 'A' in 'A list' stands for," she snarls. Gussie, an actor who has by no means reached the top of the Hollywood tree, embarks on a full-scale slanging match at a Hollywood party: "I never said you were too old for the part," her producer has to reply hastily. "It was the studio that said so." Rewind nearly 20 years, and we discover that Gussie has already got through several husbands, and believes that the more thigh you show the better, while Mary is much more the serious, thoughtful personality.

Sondheim seldom makes life easy for the casts in his shows, and here he makes things even harder by reversing rather than developing the characters as they age. But Elizabeth Marsh (Mary) and Rebecca Jackson (Gussie) turn in impressive performances as they strip back the years. Also strong are Sam Kenyon as composer - and later hotshot Hollywood producer - Frank, and Thomas Padden playing his writing partner Charley. There's many a twist and turn to this relationship, which must surely contain autobiographical elements: "It's a hit," says an amazed Frank on one occasion, "Now it's out of basement studios, and no more pianos with six keys missing". It's ironic too, for Merrily We Roll Along originally achieved just 16 performances on Broadway.

And then there's Sondheim's often hypnotic score, here given sparky big band treatment by arranger Catherine Jayes. As always with John Doyle's Watermill musicals, the cast also acts as the band. With Sondheim, every note, every single word, every pause is loaded with concentrated meaning, and the whole 12-strong cast does John Doyle's ten-year Watermill record, and Jill Fraser's memory, proud. As young, idealistic Frank, Charley, and Mary put it when they first became friends in 1957; "There's so much stuff to sing".

Merrily We Roll Along continues at the Watermill, Bagnor, Newbury, until March 8. Tickets: 01635 46044 or online at