Happily, as yet no designer seems to have cornered the market in such conversions, so there is no uniformity about them.
Here, two long, thin dining rooms are laid end to end, neither having anything in common with the other. One has high-backed, red leather bench seats that score high on privacy, the other is a long refectory-line of tables up against a wall, with a good view of all the comings and goings in the bar. You can see what neighbouring tables are eating, and watch ladies in stripy dresses clash horribly with the banquette seating.
The Abingdon's chef, Brian Baker, used to cook at the luxurious Hambleton Hall in Leicestershire (or perhaps it is Rutland again now), where he was awash in expensive ingredients, with a brigade to do the donkey-work. Such a job might be considered the apex of a chef's career, but the downside is an anxious race to win accolades, a highly charged and competitive atmosphere, and total segregation from the customer.
It is perhaps significant that a number of good chefs in recent years have forsaken all that, and have moved to small, informal places where they can be themselves, and cook what they like at prices that real people can afford. Among them are Shaun Hill (who moved from Gidleigh Park to the Merchant House in Ludlow) and Michael Womersley (from Lucknam Park to the Three Lions at Stuckton in Hampshire).
After leaving Hambleton in 1991, Brian Baker took time off to travel, then worked at the Criterion, in its pre-Marco days. He opened here in June 1995, and seems to have taken to the chef-patron role like a duck to orange sauce.
Baker supervises the kitchen, but you can see him popping out to serve tables, too, looking tall, dark and very busy as he makes vital contact with the punters. He cooks what he wants, mostly simple dishes of moules marinieres, chicken liver salad, or grilled pork chop, a style eminently suited to the circumstances, but the plain-sounding menu belies the skill that goes into some of the dishes. Main courses are priced at under pounds 10 (apart from roast rack of lamb for two), starters and puds are under pounds 5.
To get Baker's technical accomplishment at these prices is a welcome treat. The star dish of our meal was a slice of light, smooth, pink and sophisticated terrine made from scallops, studded with nuggets of red mullet. It tasted delicate, yet positively shellfishy, and was brilliantly partnered by "rustic" plum tomatoes: flavourful, mature ones that had been kitchen-dried with garlic and herbs. Their sweetness and acidity balanced the terrine magnificently, and a gentle chilli heat built up over the course of eating it.
A stunning-looking dish of bright red roasted peppers and dark green watercress ran it a close second. The central frame of this was a piece of chicory that had been braised to lose some of the bitterness, then expertly breadcrumbed and deep-fried. The bitterness of the watercress and the sweetness of the peppers made a powerful combination, and the whole dish was a lesson in how to make chicory interesting.
Main courses are mostly self-contained, and we forgot to order extra vegetables (they are charged extra, at up to pounds 2.50 a portion) - but a bowl of shelled peas and greens, and another of long, thin chips - nicely dry and perfectly seasoned - were soon rustled up.
Shelled peas are something of a rarity in restaurants, so often being displaced by mangetout; and as for the ordinary button mushrooms that came with the duck confit, I simply cannot remember the last time I saw them. Everybody, but everybody, advertises "wild" mushrooms on the menu, even when they are cultivated oysters and shiitakes, and even when their only function is to make the dish sound better than it actually is. It takes a brave man to use plain, ordinary buttons. Maybe it was the shock of stumbling across such a humble variety, but they tasted very good indeed, just what the down-to-earth cooking needed.
Less successful was the confit itself - an ordinary, well-cooked leg lacking the salty, herby, ham-like character that comes from preserving it - and the inordinate number of sweet baby onions that filled the bowl to overflowing. Minor imperfections also beset a thick chunk of marinated salmon, mostly over-zealous seasoning and searing - but these are relatively easy things for a kitchen to put right, given that the materials are good and the skill level high, and that dishes are mostly well thought out.
We shared a classically simple and expertly rendered pudding: pate sucree filled with a light, orange-flavoured creme patissiere, topped with halved prunes, with tasty amaretto ice-cream on the side.
We also enjoyed a bottle of Viognier from a list of around ten white and ten red wines all under pounds 20 (plus fizz), and paid pounds 62 for two, which included an "optional" service charge of 12.5 per cent
Jim Ainsworth is editor of 'The Good Food Guide 1996'
The Abingdon, 54 Abingdon Road, W8 (0171-937 3339). Open lunch 12noon-2.30pm and dinner 6.30-11pm Mon-Sat; brunch 10am-12noon, lunch 12noon-3.30pm and dinner 6.30-10.30pm Sun. Major credit cards, except Diner's