Sheikh Ahmed's filly deserved this valuable success having finished second to Irish Oaks winner Covert Love at York before running a good race from a poor draw in the Sandringham Stakes at Royal Ascot.
She overcame a wide draw yesterday but was always well-positioned by James Doyle, who was always close to the pace.
She cruised up to the leaders with two furlongs to go and kicked for home. The runner-up Nancy From Nairobi posed a sustained challenge but Tazffin was always in command and went on to win by half a length.
Roger said: "This has been the plan for some time. She is a talented filly who had strong form going in to the race and hopefully she should build on this as the season goes on."
Decorated Knight continued his progression with an impressive victory in a ten-furlong handicap at Sandown.
The son of Galileo, owned by Saleh Al Homaizi and Imad Al Sagar, had plenty of ground to make up on the second-favourite Pyjama Party but was well on top at the finish and went on to score by half a length.
Roger added: "Decorated Knight had plenty of ground to make up on the runner-up and I was impressed by him. We have bought his along slowly and he is a progressive three-year-old."