FORMER Hong Kong riding star Brent Thomson was one of the more unlikely trackwork watchers at Sha Tin yesterday morning. Thomson, who rode as stable jockey to Brian Kan Ping-chee and Eddie Lo, is back in the territory as he makes his way from Australia to England where he will ride this summer primarily for Robert Sangster. Looking very fit and determined to make a go of it in Europe, he said: ''It's always good to be in Hong Kong to see so many old friends and relive so many happy moments - and a few hilarious ones, too. ''It's a great way to split the journey for a few days but I can't hang around too long as I've got to get to England and get working.'' Thomson, who has taken on Steve Cauthen's agent John Hanmer to book him rides, is likely to be based in either Newmarket or Lambourn. ''Robert has some 130 horses in training. We met a couple of times to discuss things in Australia and while he also has commitments with the likes of John Reid, there should be a number of rides. ''The horses run all over the place there and John can't be at all the meetings at the same time,'' Thomson pointed out.