Marie-Castille Mention-Schaar, the French producer of Richard E. Grant’s directing debut “Wah-Wah,” would be well advised to stay away from British bookshops for the next few weeks.She might otherwise be tempted to pick up a copy of “The Wah-Wah Diaries,” Grant’s entertaining account of making his autobiographical movie, in which he skewers her mercilessly. Published April 21 by Picador, it’s a romp through the ups and downs of indie filmmaking on a shoestring, from the perspective of a highly strung artiste whose long experience as an actor has barely prepared him for the precarious reality of life on the other side of the camera. But what gives the diary its edge is the anger Grant vents against his producer, whom he calls MC. He paints her as a precious dilettante who repeatedly leaves him to dig himself out of holes she has created. Her catchphrase “But I’m the producer!” becomes an ironic refrain throughout. “Wah-Wah,” starring Gabriel Byrne, Emily Watson and Miranda Richardson, opens May 12 in the U.S. via Roadside Attractions, and June 2 in Blighty via Lionsgate UK. The story of Grant’s troubled childhood in colonial Swaziland with an alcoholic father (who once tried to kill him) and an absent mother, it got rave reviews when it premiered last fall at Edinburgh and Toronto. But if Grant is to be believed, everything was achieved despite — not because of — his French producer. Key episodes in the book describe him begging the Swazi king to let him start shooting the next day, when he belatedly discovers that MC has failed to secure the necessary work permits; and prostrating himself before U.K. officials to bend their rules when he similarly discovers that MC has left it too late to apply for official UK/French co-production status. Arguments over financing, logistics and creative issues continue all the way through to the final cut — although once shooting starts, MC becomes an increasingly absent figure, so completely had her relationship with Grant broken down. That explains why the movie carries a “with special thanks” credit to the “marvellous” catering crew. Insiders say this was inserted by MC because Grant never allowed her to mingle with anyone else on set. Some incidents are regrettably not mentioned, such as the meeting when Grant threatened to “drive a stake” through her heart in front of a dozen witnesses. These included Jeff Abberley of the pic’s U.K. financier Scion Films, who effectively took over as the lead producer as shooting progressed. He says the experience has put him off ever doing another French co-production. “There were lots of incidents, far more than I’ve experienced on any other film,” he recounts. “There’s a big cultural difference between the ways in which a French producer approaches things and the way we work in Britain. MC had this peculiarly French concept of the producer as auteur, but once this idea was deflated, she lost interest.” Abberley emerges with credit from the diaries, and he reciprocates the compliment by describing Grant as “wonderfully collaborative.” Even though Grant was telling a story agonizingly close to his heart, he was always open to other people’s suggestions to improve it. But Abberley cautions that Grant’s wasn’t always privy to the full drama behind the scenes, so his account of events is occasionally unreliable. Grant simply recorded his impressions as he went along, just as he did with his previous book “With Nails” about his acting breakthrough in “Withnail and I.” The lesson is clear for producers thinking of hiring Grant as a director: He’s a genuine talent who can be a joy to work with, but if you fall out with him, he won’t be afraid to take his revenge in print.