First I’ll give details of a rather marvellous offer. Spend £75 a couple on an à la carte meal in Malmaison’s restaurant on a Sunday evening and you can have a bed for the night in this luxurious hotel for just £1 – subject, of course, to availability. Rosemarie and I did consider trying it for ourselves, but since we live only half a mile away the idea seemed slightly absurd.

Our very proximity to this one-time prison is the reason we have used it so often since its splendid conversion in 2006. A definite must in every year since has been its New Year’s Eve party at which chef Russell Heeley and his team supply a buffet of near-unparalleled magnificence. As 2009 dawned, we were dancing off this banquet to a rock’n’roll band in the restaurant (pictured right) cleared of furniture for the occasion. We vowed at the time that it would not be long before we came to dinner here again.

Last Friday, the penultimate day of January, I decided to book for that evening. Such is the popularity of the restaurant that I could only be offered a table at 6pm or 9.30pm – the first much too early (high tea, anyone?), the second a little too late. But the second it had to be. Hotfoot from the private view at Modern Art Oxford, we had three-quarters of an hour to kill before we could eat, and killed it over glasses of Sauvignon Blanc in nearby Tootsies where the courtesy of the staff has impressed me in the past. They acquitted themselves well on this occasion, too. After hearing of our long wait caused by a shortage of glasses (the place was packed), the manager Kristy offered us free drinks to compensate.

Malmaison was full as well, and we soon found out why. Many people were there on another promotional offer – a two-course meal for two and a bottle of wine for £29. Moving into combative, slightly Norah Battyish mode, Rosemarie demanded to know why we were ruled out of this. It was because we hadn’t booked earlier, on line.

Soon I moved into assertive customer mode, too, with the request to be moved from the side cell in which we had been seated. It was clear that others present in the room would not be lowering their voices below a mild bellow as the night progressed.

“Those side rooms are noisy,” acknowledged the member of staff who moved us (rather grudgingly) to a table in the open part of the restaurant.

Here, by contrast, the company could not have been more serene. To my right, at the next table, I encountered the unmistakable features of Sister Frances Dominica, the founder of Helen and Douglas House hospices, who was dining with two friends.

“Hope she has not been to the loo,” I thought, aware from what Rosemarie had told me that the same blue comedy that had surprised me in the men’s was being relayed there as well. Little was left to the imagination in the matter of who was doing what, and with what and to whom. I am probably quite wrong, however, in supposing Sister Frances would have minded any of it.

During my own trip to the loo I had, at the suggestion of one of the bar staff, gone farther along the corridor to inspect the prison cell that had been left untouched during the hotel conversion. I had not seen it before, and did not find it comfortable to look at. The three metal beds crammed into the tiny spartan room spoke of much discomfort and misery endured there over many years by its occupants.

After this evidence of man’s inhumanity to man, so recently exhibited here, it was a relief to return to the comfort of the restaurant, and our dinner. The menu had been changed a day or so before and seemed to me to reflect (dare I say it?) the tastes of these economically embattled days, especially among the starters where such austerity favourites as mutton and barley broth, terrine of corned beef and Scotch egg were to be found. Belly of pork with black pudding was among the mains.

My starter was in less traditional style, an attractively presented terrine composed of al dente slices of that deliciously aromatic vegetable, celeriac, interleaved with layers of chopped wild mushrooms, encased in gelatin and leek skins. It was served cold surrounded by a warm thin ‘soup’ of vegetables à la Greque, button onions prominent among them.

Rosemarie had soup proper, although this classic version of French onion could almost have been considered a stew, so substantial was it in terms not only of its onion content but also of the croutons and cheese that topped it in gratinée style. She enjoyed it, but the spoonful I tried seemed bland, a function of the onions’ sweetness, I guess.

Her main course was a fishcake, which is often considered an austerity dish, though not as supplied here. Nearly six inches in diameter, this was not the usual patty of uniformly distributed potato and (not much) fish but rather a crispy potato case lavishly filled with tender flakes of cod and salmon.

This most impressive dish was further enlivened with parsley sauce and buttered wilted spinach. She also shared my slightly crunchy green beans which came with (a nice touch) a topping of fried shallots.

My main course was well received, too. This was a juicy chunk of seared monkfish, pearl shiny within, with pieces of fatty, bacon-like Iberico ham in a warm vinaigrette.

Further judicious touches came with the baby glazed carrots and the incorporation into the juice of chewy Spätzle, baby dumplings of egg noodle.

Rosemarie ended, as usual, with a chocolatey pudding – this time a dark chocolate and orange tart, which she judged so-so rather than sensational. I meanwhile finished the last drops of the slightly flowery white Rioja.