IT was no accident that defending champion jockey Basil Marcus set a professional best for Happy Valley last weekend when riding an incredible 440-1 five-timer. It was the first time this has been achieved at the city venue since racing turned professionalin the early seventies. But then no jockey has ever worked harder for his rides or studied the form more assiduously than the naturalised South African who, for the record, was born in Zimbabwe. The pugnacious Marcus has become a firm favourite with punters as well as trainers and owners since arriving in the territory the best part of three seasons ago to ride as stable jockey for Lam Hung-fie. That position soon merged into a kind of de facto Club Jockey as Marcus, a great ambassador for the sport, and Lam distanced themselves midway through the first season when it became clear that the stable couldn't guarantee the jockey enough winners for the following year. Marcus is as determined as they come. Beneath that smiling exterior is a competitive heart and a desire for one thing - winners. In that first season he only narrowly failed to beat the late Noel Barker to the jockeys' championship in an epic duel which went all the way to the last meeting ofthe campaign. Marcus then ran away with last season's championship, sewing up the title a good few meetings from home in a year which saw him average more than one winner a meeting - 69 for the 67 meetings run. Winners have not flowed quite so thick and fast this time round but that was always to be expected. Marcus is now stable jockey to David Hill and stable riders of today are always going to struggle to match the winning tallies notched up by Club Jockeys of the past. But while the winning total may have ebbed, the desire for success burns just as fiercely. And it is this incredible singlemindedness which sees Marcus punching and pushing away for all his worth in a Class Six event in the pouring rain during a mundane midweek equitrack meeting. He will dispute the running to the first bend in these events on the dirt as much as he will in any Class One contest worth millions to the winner. This is the nature of the man. He lives to win. See him leaving the course after a day without a winner and the bounce in his step has gone. It doesn't matter how well he's ridden or whether or not his horses had any chance in the first place. See him after just one win and he's back to his normal affable, approachable self, full of quotable quotes and the pressman's dream. But he doesn't just win his races on the track where that seemingly ungainly bobbing style of his just keeps on getting results. The perfect illustration of this was when his mount So Easy rallied under full Marcus pressure to short head Star Of Marble on whom Tony Cruz was riding at his classic flat-backed best. ''I don't mind anyone commenting on my style,'' smiles Marcus. ''As I know that it works and works well.'' Indeed Ivan Allan sees plenty of the legendary French jockey Freddie Head in Marcus. ''They just keep pushing away and they keep winning. You can't argue with that,'' says Allan who feels Marcus put up one of the displays of the season when second on Jet Speed recently. Marcus also wins many of his races off the course through his constant study of the form book and his replaying of race videos. ''I don't know much about the form of the overseas runners for the International Cup,'' he said the other day. ''But I will do on the day. I'm arranging for videos of their races and will be going through their form.'' This is all part of the master plan and trainer Hill have hatched to give the local champion, River Verdon, every chance of defending his Invitation Cup crown. Come next Sunday, Marcus will know every one of his opponents. Their form credentials and their colours will be filed in a mental dossier so that when the gates burst open he will be able to react to all manner of circumstances. Who are the dangers should the pace be slow? Who to follow if the gallop is fierce? Which horses to avoid as they are likely to be the first to weaken and to fall back into a rider's face? Marcus will have worked all this out and will ride his race accordingly a week on Sunday. ''I'm very, very happy with the way River Verdon has progressed from each run,'' he adds. ''David really has done the perfect job on this horse who is getting to peak fitness without even knowing it. ''He's a tall, athletic horse and this is a very skilful way of preparing him. If you have them too fit for one run they don't necessarily progress for the next. This is something David has avoided and River Verdon is getting better all the time. ''I can't say too much about the opposition at this stage but what I can say, knowing our horse's ability and the fact that he is playing at home, is that he is the one they will all have to beat.'' As for his riding arrangements, Marcus has confirmed hisretainer with Hill for next season and will also be riding a good deal for Ivan Allan. ''This season has been immensely important for me,'' added Marcus. ''It proved I was no flash in the pan, that I can consistently gain results. ''Next season I can startthinking about winning championships again, this has all been about consolidating what I have already achieved here.'' With such powerful stables as Hill and Allan behind the never-say-die Marcus, there will be plenty clamouring to get on him for the championship at the start of next season. Any prices out there?