Each week on At Your Service (RTÉ One, Sunday, 8.30pm) – the business makeover show that  has modestly become a fixture of RTÉ since 2008 – Francis and John Brennan step out for a brief confab to review the situation.

While the hotelier brothers will advise B&B and guesthouse owners to radically revise their ways, often meeting pained and stubborn resistance, the structure of At Your Service is far less negotiable. It's hard to decide if these familiar and worried brotherly consultations more closely resemble scenes from an old police procedural, like Dragnet, in which detectives glower together over intractable investigations ("Something about that widow just doesn't add up"), or the gods of a Harryhausen film, staring into the pools of Mount Olympus wondering about the deluded ways of mortals below. Either way, it always gives a handy synopsis.

Here, they exchange notes as they leave their first meeting with James and Joanna Fennell at Burtown House, a grand old pile built in 1710, which is still owned by descendants of the original family but is struggling to survive.

“I think they’re going from a cottage-food operation to a major commercial food operation and therein lies the risk,” says John, the more straitlaced of the brothers, sagely. “Absolutely,” replies Francis, the show’s flamboyant star. John’s attention to detail and turn of phrase are quite remarkable, though. “Food will eat you up and spit you out,” he tells the couple, a photographer and interior designer building a new restaurant on their grounds. Maybe it’s the nightmarish inversion of the image, but their wide eyes and fixed smiles often convey sheer terror.

Francis, of course, has the better bedside manner, usually offering dire analysis with fey reassurance, while John is like a Cassandra, precise, insightful and confident his predictions will go unheeded.

“I have said my piece,” he concludes, after stern appeals to reposition a car-park, abandon plans for a pizza oven, and not rely on the commitment of their “lovely Italian chefs”. Sure enough, they ignore his advice, and turn the car-park into an oven (“The warmest car-park in the history of the state,” remarks John, dryly), fail to install the actual one, and lose the lovely Italian chefs – albeit temporarily.

The show wouldn’t be so entertaining, of course, if this sensible advice was taken without resistance. So much of its verve is taken up with trying to shake some sense into the clients. Previously, they have even sent spies into B&Bs to give unvarnished reports. Here they insist on trial runs and surveys that yield reports of service that is “unorganised and under pressure”, which seems to sum up the whole operation, finally running over time and over budget.

There is something instructive about the efficiencies of the show itself, though, filmed over long periods (in this instance six months) to provide 25 minutes of easily absorbing television. The Fennells just about pull it together in the end, and it's heartening to see John delivering plates during an opening-night crisis, or Francis gamely apologising for delays. Four out of every five restaurants close, John reminds the Fennells soberly, which sends you scuttling on to Trip Advisor, reassured to see that, six months later, The Green Barn is still going.

The gospel according to Francis and John is one of transformation when transformation is hard. The irony of the show is that it offers this message within a reassuring formula, unaltering and somehow still sincere. Don’t ever change.