This fund-raising event has taken place every year since the association was founded in 1973, the money going towards veterinary bills and travel expenses incurred on rescue missions. Pugs made homeless through house repossession, alone after their owner's death, stranded in pet shops: the intrepid Mrs Dudley and her committee members drive all over the country to rehouse them with suitably loving owners.
Today, they have their parade. Picnics are in full swing behind car boots, children are playing beneath a scorching sun, pugs are everywhere: on laps, over shoulders, cradled in arms, in cages, between legs and under skirts in pursuit of shade.
There is no fighting, no snarling or barking, with only the odd bit of bottom sniffing, and not an unsolicited mount to be seen. The only noise is the steady pant, pant, pant as scores of squashed-nosed dogs fight against the heat.
The arrival of an ambulance seems a wise precaution. But this is no ordinary ambulance. A great kaftan of a woman disembarks and something blob-like is eased into a pushchair.
It is George, 13 years old, a pug rescued two years ago after his owner died, and now suffering from severe rheumatism and arthritis. 'He tends to fall over,' explains Peter Fairall, his new owner. 'So rather than have him falling about we put him in a pushchair. Whoops] Steady George . . .' Peter's voice trails off as he shoves George's bottom, sliding over the back end of the pushchair like some feisty blancmange, back on to his red velvet cushion.
Meanwhile, his son, Robert, who has just been photographed with pug number two, Jasper, over his shoulder, is frantically wiping the hairs off his Meat Loaf T-shirt. 'I don't want anyone to think I've got dandruff,' he says.
'I'm a bit of a make-do-and-mend-artist,' continues his father. 'I bought the pushchair and the ambulance at a car boot sale two years ago . . .' 'Because,' chips in his wife, 'I'm too big to get in and out of cars.'
The Fairall family doesn't conform to type. Ever since Queen Victoria kept pugs, they've been society dogs, adored by the likes of Edward and Mrs Simpson, Winston Churchill and, today, Glyndebourne owners Sir George and Mary Christie. A more typical owner is 22-year-old Ed Lepper, slumming it today in baseball cap and shades. His family have spurned retrievers for pugs. 'Having a pug is eccentric enough to be extremely cool. Some small dogs are pretty annoying, but pugs have personality and charm and are very intelligent.'
That's not all. 'A lot of dog in a small parcel', pugs make excellent guard dogs, top breeder Rosemary Greenwell explains. 'They've got a big dog bark, a deep frightening bark for burglars.' It is a ferocity lost on some, concealed as it is within a 'teddy bear quality'.
What's more, adds Rosemary, 'pugs never rush off hunting which, surely, is a great advantage'. Indeed. When one pug wanders off no more than 10 yards away, its owner is panic-stricken. The pug is quickly spotted. 'Mummy lost you,' she exclaims, and nestles lovingly into her pet's wrinkles.
One woman's T-shirt declares her to be 'Pug potty'. 'My cleaning lady went home to Hong Kong for two weeks - yes, I probably do pay her too much - and had the T-shirt made for me. I imagine they've probably got pugs in Hong Kong, the ones that haven't been eaten by the Chinese, anyway. This is Toby, he's three and very sexy.'
The tea room is packed. Elbows are out for the Victoria sponge. Everyone is chattering away and the floor is teeming with pugs - apricot, fawn, black. The talk is breeder babble, all 'tight little twists' and 'good firm hindquarters', mixed with cocktail party pleasantries - 'This must be the famous Geisha]' and 'Are you the lovely Bertie?' - as the tension grows for the highlight of the fancy dress parade.
The Pug Dog Club bric-a-brac stall is doing a roaring trade in reject Tupperware and secondhand bath caps. The pug paraphernalia on the Welfare stall is selling even faster: stylish pug tea towels and washcloths, pug-shaped cushions, handmade Victorian-style Christmas cards featuring superimposed cut-outs of pugs, pug bookmarks, even pug poetry.
Meanwhile, children are getting bored. The tombola has run out of prizes and the raffle and auction are long finished. Mrs Brown, who usually organises the games and the pug jockey race, has broken down on the M25. A makeshift game of musical chairs takes place to a car cassette player. The first boy out bursts into tears and his father chastises him for being a cry baby.
At last, the school bell is rung, heralding the fancy dress parade. There is a flurry of activity as pugs are manoeuvred into velvet and plastic. Ossie can't wriggle out of his Robin Hood brown felt breeches fast enough. His sister, Sophie, sports her Maid Marion medieval hat and veil, plonked on her little head like a child's party hat, with an air of dignified resignation. A pair of gate-crashing collie dogs survey the scene with bemused contempt. Some of the contestants are given short shrift by the judge. Queen Victoria is definitely not amused and the Good Fairy looks mad as hell.
'Look at Robin Hood's money pouch]' says Mrs Dudley, whose attention to detail is far sharper than that of the judge, who has already reached the end of the line-up. 'That's what he's robbed from the rich,' grins his owner, pointing to the pug-sized drawstring pouch glistening with rapidly melting gold chocolate coins. Amazingly enough, neither he nor any of the other contestants are trying to scoff the booty.
''I do love Captain Scarlet tossing his head,' says Mrs Dudley, getting into the mood of things. His grey bellboy cap with red trim and matching trouser suit elicits murmurs of approval and knocks the spots off the unseasonal bundle of tinsel and baubles masquerading as Christmas.
'Have you seen the bell on his tail?' shrieks Phyllis, evidently worried that the judge may have missed this vital detail. The shrieking may have helped. Christmas gets fourth prize while Captain Scarlet only gets fifth. His owner is devastated. The Captain, in keeping with his super heroic image, looks unconcerned. Lorraine, meanwhile, is delighted that all her hard work, which included searching for the right-sized chicken feathers for Robin's arrows, has paid off with first prize.
Don't pugs mind being dressed up like PG Tips chimps? 'Oh no]' says Lorraine. 'Look at him, he loves it, as long as it's not too hot.' Ossie is being carried and looks as if he's about to pass out. 'He's such a wally. I had golden retrievers before but I didn't dress them up. You're more like a baby, aren't you Ossie? Coochie-coo.'