TRAINER David Hill holds the key to the Double Trio as racing returns to the Happy Valley turf tomorrow night after yesterday's big Lunar New Year meeting at Sha Tin. And relishing the return to the tight city track will be sprinter Echo, who scored a devastating win over the minimum trip on the equitrack there last time. It was one of the most complete, comprehensive victories seen on the track this season and, not unnaturally, earned the sprinter a promotion to Class Two. In completely obliterating a Class Three field last time, Echo jumped from the outside and was over and on to the rails before the rest had virtually hit their stride. Garlic Lad was the other handy performer in the field with a sharp 975-metre time to his credit but he never got a look in. Echo has drawn in barrier five in the full field of 10 tomorrow night but if he clears the gates with the alacrity shown last time, it is still difficult to see them catching him regardless of the rise in class. One who could beat him out, or keep him wide, is the battle-scarred Always Early, who is basically unsound, but who does scamper along and has been gifted with the rails draw here. Always Early would be unlikely to see out even this short trip and when he comes under pressure it should be the end of him. But he will keep Echo motoring on his outside. Monkey Saint has pace and is a last-start winner at Sha Tin for the team of trainer Derek Cruz and visiting jockey Alan Munro. It was the gelding's first win and he is not the most reliable of horses although the minimum trips are clearly his forte. Silent Majority missed the start last time and took little meaningful part after coming back from the break but should be improved by the run and his work has picked up. He is one who also appreciates this trip and has never been one to shirk the issue in the past, boxing on well when right up against it. He deserves to be at a shade of odds but is worth including in the DT legs. Hill saddles up Mustang in the first leg of the popular bet and there is going to be no fancy price about this fellow. He won as he pleased at Sha Tin last time and comes into this carrying 140 pounds. He remains in Class Three and does look fully capable of scoring in better company than he is currently keeping. As far as a banker bet is concerned it is difficult to go past this fellow although the weight could be a steadier and he must negotiate the tricky Valley bends. But in this company he does represent class and must be followed. He will also have the services of the Valley ''King'', Basil Marcus, and the odds will reflect his solid winning chance. There is a weak look about the rest of the field although Overtaker has been known to put in a top run at the city track when he is right and he could spring up here - at least running into the frame. Trainer Bruce Hutchison takes a voluntary promotion with Hankow Star who found the weight too much last time and disappointed a week ago at the same venue. He has engaged Irish champion Mick Kinane for the ride and given the lenient weight over a trip he should get, Hankow Star is worth considering as a DT leg. Great Time ran an improved race last time and is worth modest consideration while Gem Of India ran a fair trial at the course recently and could pop up in a minor place.