WHEN you rule your kingdom, perhaps, in reflective moments, you ponder what might happen to your throne once you have gone. So it is with Colin Jackson. The Welshman, world sprint hurdles record holder indoor and out, is not ready to abdicate, but wants Britain's hurdling dynasty to continue. The man he is grooming to wear his crown is Scotland's Ross Baillie.

The 21-year-old, who runs at tomorrow's Scottish Indoor Championships in Glasgow, has already lowered his own national indoor record for 60m hurdles this winter to 7.77sec, and hopes his Kelvin Hall race will bring a native record and a qualifying time (7.75) for the World Indoor Championships in Japan, from March 3 to 5.

If not, he has a further chance next weekend at the AAA indoor championships in Birmingham, after which the British team for Maebashi will be chosen.

Since before last year's Commonwealth Games, where he set a Scottish record (13.80sec) for the 110m hurdles, Baillie has shared an apartment with Jackson, in Bath, where the pair are under the guidance of Malcolm Arnold, widely acknowledged as the world's finest hurdles coach.

''Colin wondered, last winter, where the future of the event lay, and thought Ross had the best chance of making it,'' said Arnold. ''Colin looked all round Britain at the contenders. He picked Ross because he was a good hurdler who could also sprint.

''He was being looked after by Bob Sommerville, and we spoke to him first.'' Sommerville, the highly regarded Glasgow coach, had begun helping Baillie after the youngster had abandoned high jump aspirations, transforming him into a prolific hurdles record breaker and British schools pentathlon champion and record holder.

Sommerville and Baillie visited Bath to see the set-up which Arnold, Great Britain's former director of athletics performance, was building after stepping down to return to hands-on coaching.

Sommerville is to be complimented on the way he has handled the hardest task any coach can face: letting a protege go when someone else has more to offer. He had given Baillie roots to grow, and wings to fly. ''There was nobody to challenge Ross here. I'd have been foolish to deprive him of the chance,'' said Sommerville. ''Any coach who thinks only of himself should not be coaching.''

Bath's hothouse environment is one which new Scottish performance and excellence manager, Meg Stone, is keen to see in Scotland once coach development programmes are established. ''I'd give anything to have a Malcolm Arnold here,'' she says.

Allison Curbishley, Scotland's 400m silver medallist from Kuala Lumpur, is being transformed into a one-lap hurdler by Arnold, who shares Jackson's view that she can follow Sally Gunnell as world and Olympic champion. Also in his group is Melanie Neef, City of Glasgow's former UK 400m No.1, and Fife's Scottish 100m champion Ian Mackie, who will accompany Jackson to Australia this winter.

''If Ross qualifies for the world indoor, he will also go to Australia,'' said Arnold. ''I'm trying to give him the same opportunities which we put in place for Colin. The rest is up to him. There is only one Colin Jackson, but there is scope for Ross to head the next generation. Nigel Walker ran 13.51, before switching to rugby. There is no reason on earth why Ross cannot run as fast. After that, who knows? I cannot see Colin continuing to compete beyond 2001.''

Baillie, still 20 when he ran in last year's Commonwealth final, finished the year ranked fourth in Britain, behind Jackson, Tony Jarrett, Andy Tulloch, and Paul Gray. ''They are 31, 30, 31 and 29 respectively,'' says Baillie, who has clearly done his homework, ''and Gray, the youngest, considers himself a 400m hurdler.''

Baillie's parents, Sheila and Hugh, were Scottish sprint hurdles and 400m champions, but their two sons - 17-year-old brother, Chris, has already eclipsed two of his elder's age group records - have surpassed them.

Ross was initially into football, then judo. He tried the high jump, but could not match Martin Pate. ''We could never find an event for him until we asked Bob, and Ross suddenly blossomed as a hurdler,'' says Sheila, a teacher.

Last weekend the younger Baillie, previously a Scottish age group high and long jump record-holder, was credited with removing his brother's national under-20 hurdles record of 8.05, but the official electronic mark showed he missed out by two hundredths.

The pair meet again tomorrow, however, and even if he cannot yet beat his brother, he hopes to write out another of his records - a sibling rivalry set to run and run.

Two hamstring injuries last winter, one to each leg, made the elder Baillie's progress remarkable. ''This year training has been uninterrupted, so I am stronger, more aggressive into the barriers, and better off them,'' says Ross. ''Some of Colin's fluency is rubbing off. I'm more consistent.''

Though he has set personal bests at every major event - when fourth in the world junior championships, fifth in the European Under-23s, and Commonwealths, the lottery has downgraded him. ''I've gone faster every year, yet have been dropped by the UK level of the lottery. I don't want to sound whingeing, but reverting to funding by Scotland effectively makes me thousands worse off. I am scraping by. If it were not for #2500 from Barclaycard, I'd have to get a job, training in the evenings, which would not be with Colin. It may come to that, and would not help my athletics.''

Baillie is ranked fourth in Europe under-23, a potential medallist at this year's championships in Gothenburg, top-20 in the world under-23, and front-runner for the British No.1 mantle after Jackson goes. You might think that was what the Lottery Sports Fund was set up to nurture. His experience is disturbing.

This weekend he is likely to join Elliot Bunney, the former Olympic medallist turned agent, whose first job will be to find quality races and explore sponsorship opportunities.