This is a family evening for authors and cast, if not for the audience. Ray Cooney who directs, shares the writing credit with his son Michael, while the three brothers of the title are played by three of the four McGann brothers, respectively the mature Joe as a much-married Tom, Stephen as the sly Dick, and the appealing, squeaky-voiced Mark as dozy hospital porter Harry.
In what at first appears to be the basic plot but is merely a book-end device, charmless Tom and his anxious wife Linda (Hannah Waterman), eager to adopt a baby, are waiting for the lady from the agency to turn up and carry out one last check to ensure that they and their rented Kennington garden flat are fit for purpose.
But on this crucial day of days their dreams are scuppered when Toms brothers, Dick and Harry, arrive with ideas of their own.
The laboured, farcical events that follow mark a complete departure for Ray Cooney: no infidelity, no breast-fondling gags in fact, no hint of sexual shenanigans at all. Nor are there holdalls full of used £50 notes; not even the usual strident snooks cocked at camp young men in antiques or middle-aged bachelors.
Instead we have a production that starts like an express train going off the rails, which then except for the interval scarcely stops for breath or coherent plot development for the next two hours.
As a master farceur Cooney knows every trick in the book except restraint. Co-authoring with his son, also with farcical form, they deliver a multilayered play with enough source material for half a dozen comedies; alas, none sufficiently developed nor strong enough to carry the evening or give it a sense of comic direction and focus.
The baby plot merely serves to introduce an authority figure, an unrewarding role for Louise Jameson as the prim Mrs Potter from the agency, carrying a clipboard and a sour expression. But she is regularly pushed into the next room without protest, and departs almost unnoticed except for her rude parting gesture.
Likewise, Dick has a van parked outside crammed with contraband fags and brandy, brought from Calais. But although this is given a desultory investigation by a complaisant copper on the beat (Mark Wingett playing it dead straight), PC Plod is more interested in missing tax discs than tax evasion and it almost immediately fizzles out as a comedy development.
More promisingly, in a throwback to 1990s world events, two illegal Albanian immigrants, a Kosovian (Brian Greene) and his pretty young granddaughter Katerina (Sarah Wateridge), are also lurking among the ciggies and booze.
But what could have been an opportunity for laughter in the face of tragedy resolves into crude mistaken identity, an excuse for admittedly brilliant mime exchanges, each getting a round of applause, and flatulent noises from under the sofa bed where the old man struggles to toot his trumpet while in hiding.
A sub-sub-plot also introduces an incompetent Russian Mafia hit-man (David Warwick) with a briefcase full of counterfeit passports to be exchanged for cash. But his ten-grand asking price seems hardly worth flashing a gun for, and the man simply succumbs to the brothers ruse, and is too easily captured in a loosely tied bin bag.
Perhaps the main McGuffin is Harrys ridiculous, not to say distasteful plan to bring body parts, wrapped in Sainsbury carrier bags, from the teaching hospital where he works.
He intends to bury these smelly leftover remains under the patio, sprinkled with lemon and cooking salt to accelerate decomposition, then to be discovered by a team of conservatory builders, thus devaluing the asking price of the flat to make it affordable for the hard-up Tom and Linda to buy.
But when these severed limbs, head and other organs are finally revealed they are about as likely as Blue Peter papier maché models, neither gruesome nor believable, and would have been much better left under wraps.
True high-spot of the evening reveals the McGann boys as deft clowns, when at one point Tom tosses a couple of lemons at Harry, who niftily heads them straight into a bin bag held open by Dick. Can they really make this trick work every night of the run? Whatever, its a great moment of performance art.
As a long-term Cooney fan I hate giving a thumbs-down to this late work which follows his ever successful toiling in the vineyard of farce for half a century.
But what do I know? The evening is probably critic-proof, witness the way that the audience applauded every set piece, laughed at the tongue twisting gags, arm waving and slick double-entendres, and went out into the night on a buzzing, happy high.