WITH a twirl of his whip and a cheery grin, Classic-winning jockey Walter Swinburn announced to Hong Kong punters with a Happy Valley treble yesterday that he's here on business. Swinburn, who won the 1,000 Guineas in England last season and cut a swathe through European Group races, rode two winners for David Oughton and one for David Hill. That's taken his tally to four winners in two days and he said: ''You couldn't ask for more than that. What a beautiful way to start.'' His class showed as he completed the treble on Hill's Gladstonian in the eighth event. He got the better of Jackie C. K. Tse in a great duel to the line and, inches before it, gave his whip a celebratory twirl. The Irishman with the infectious, impish grin had arrived. He has been in Hong Kong on many occasions but has never had the impact that his success in Europe merits. It was the only day meeting scheduled for Happy Valley this season but with a billion dollar turnover and a good crowd basking in the sun, there is clearly need for more of them. Trainer Oughton had his best day for some time with a treble and Hill prepared for Sunday's International Cup with a double. Compradore completed the double initiated by the Swinburn-ridden Gladstonian and Hill said: ''I was very pleased with that result. He likes Happy Valley and I thought, even though it is short of Compradore's best trip, that he would win it.'' Irish champion Mick Kinane and Hong Kong kingpin Basil Marcus are both in Japan riding in a Super Jockeys' Series - and, as a result, missed out on four winners. But with Tony Cruz drawing a blank, Marcus is only adrift of him on minor placings. It was a great day for Racing Post's England-based tipster, Topspeed, who tipped the day's two biggest quinellas. He landed the $1,100 quinella in Race One and followed up with the $2,450 payout in Race Five. And Robin Parke chipped in with five quinellas and the last two tierces.