On the hunt in London for good antiques.

When I awoke on that warm Sunday morning in London, my only conflict was how to pass the final few hours before leaving for Heathrow Airport. Would it be a farewell jog in Hyde Park, a stroll by the brilliant blooms of Kensington Gardens, or one last long indulgent English breakfast, cold toast and all?

''How about that antique market?'' asked Pamela, my wife, posing a question that until this latest visit would have met with as much appeal as asking me to go to a dog show. Thirty minutes later, having called Pan Am to put off our flight from 10 a.m. to noon, we were in a cavernous taxi - gold and not black, it so happened - bound for the Camden Lock market in north London.

England in general and London in particular can easily inspire a dormant interest in antiques hunting these days. There seems a bottomless source of curious bits and pieces, which at the recent exchange rate of $1.30 to the pound come more cheaply than ever. Whereas antiquing had always conjured up thoughts of bidding for a Gainsborough at Sotheby's or Christie's, it was suddenly clear one could have just as much fun hunting for a sterling silver toast rack for less than (STR)25.

We learned the hard way, by prowling and buttonholing, by asking naive questions and using considerable shoe leather. The first lesson is that antiquing can be carried out at three kinds of commercial enterprises: antiques centers, markets, and fairs. Fairs, the most difficult to track down of the three, move about randomly and more or less weekly from one tourist hotel or large public hall to the next.

Antiques centers stay in one place under one roof. These warrens of stalls and shops displaying glassware, china, art deco objects, silver, and rare books are open from 10 to 6 Tuesday through Saturday. It was at several of these centers, of which London has half a dozen notable examples, that we underwent our baptism of fire. The first foray took us to a phantom place with an enticing name that still appears on most London tourist maps. Alas, the Kensington Antique Hypermarket was no longer there, replaced by a collection of trendy clothing shops.

So we headed for Chelsea, whose ever lively King's Road has three prominent antiques centers, all on the south side of the street: Antiquarius, No. 135-141; Chenil Galleries, 181-183; and Chelsea Antique Market, 245-A. Moving from one to the next and back again, we found the dealers eminently patient and generally willing to cut 10 to 20 percent from their announced prices. The quest was narrowed to two shining curiosities: sterling silver toast racks, in which the English stand up their rows of cold toast (and which Americans sometimes convert to letter filers), and little glass bottles topped with silver caps, devices Victorian ladies used to hold toothbrushes and other toiletries. We bought one of each and retreated to the hotel, primed for new challenges.

Antiques markets, the third kind of gantlet, at first seemed less than inviting - especially after I stole away one Saturday morning to Portobello Road and found the several blocks as thronged and noisy as a Middle Eastern bazaar, and almost as hot. We were to leave the next day, Sunday, so we had missed the Bermondsey (or New Caledonian) Market, a reputedly enticing institution that hums from dawn until noon every Friday, south of the Thames. It was on Saturday night that I phoned my only titled friend, Lady Hartley, who runs a bed-and-breakfast house in Fulham, and learned about Camden Lock. ''It's the best market at the moment,'' said Lady Hartley, ''but do get there early.''

As we drew up to Camden Lock (a (STR)4 taxi ride from central London or a subway ride to the Chalk Farm Station) we were greeted by the sounds and smells of a market coming to life. It was 9 a.m. and dealers were laying out books, clothing, jewelry, old sewing machines, a windup portable Victrola under striped awnings. Behind an open grill, young women in T-shirts were frying full breakfasts - bacon, sausage, the works - for (STR)1.20. Two dozen would-be dealers milled about in the sun, hoping to be awarded the last few stalls and booths.

Faced with a deadline of a noon flight, we moved quickly up and down the rows , the sharper-eyed Pamela a step or two ahead scanning the endless merchandise. I made a brief detour around the corner to the tiny Camden Lock harbor where colorful water buses were tied up, waiting to make the 50-minute ride to Paddington and the London Zoo. Set back from the boats are tiers of shops - pottery, pine furniture, knits, arts, and crafts - that are open on weekdays, and worth a trip on their own to Camden Town.

Scarcely breaking stride, Pamela picked up a small painted china jug with matching bowl for (STR)8 from a man who also displayed assorted pieces of scrimshaw on his table. Fruit, vegetables, flowers, even Sunday papers were being set out. Heeding Lady Hartley's advice, we strolled - no, hurried - 100 yards up Chalk Farm Road to the Old Stables Indoor Market, said to hold the choicest of Camden Lock's bargains.

This white brick building with high overhead beams, lined with endless rows of stalls and enclosures, still carried the scent of its former use. I stopped to finger two heavy Victorian police truncheons and began to move on. ''I can get you almost anything,'' said an eager Kevin Trevor, late of Birmingham and new to the London antiques circuit.

Pamela was across the aisle, bargaining for a china toast rack and glancing expectantly up the row of stalls. ''We can always stay on and take the 2 o'clock flight,'' I said. ''No, let's go,'' she said. ''I could spend hours and days here. It's probably a blessing we have to leave.''

Camden Town, we'll be back.