The coloured poles proved to be the key to success - and failure - in a nail-biting finish to the Blarney Castle international horse trials yesterday.

Just one of the overnight leaders held on for victory in yesterday's final show-jumping phase and that was Heinz Werli of Switzerland, who claimed honours in the three-star invitational despite knocking three fences with Kilnacross. But the three feature classes all produced a reshuffling as lowered rails dropped horses down the order.

New Zealander Paul O'Brien, who had taken the lead in the two-star after a Friday dressage test on Horoscope, maintained his advantage with a footperfect tour of the cross-country track on Saturday. But a single error yesterday was enough to drop him to third, allowing Thursday's dressage leaders, Fraser Duffy and the mare Oakengrove Rainbow, through to the winner's enclosure.

British-born Duffy is now based in Fethard, Co Tipperary and his trainer Sue Smallman was also responsible for producing a stunning performance from Rozzie Watson who, at 19, was one of the youngest in the field.

Watson was lying fourth with Floating after the dressage, despite a nasty moment at the start of the test when the Cruising mare reared three times in the first halt. An immaculate clear across the country was mirrored in yesterday's show jumping to leave Watson second in her first two-star ahead of Kiwi Olympic team member Paul O'Brien.

There was an even more dramatic reversal of the placings in the one-star competition, with overnight leaders Caroline Bjoerk and Just Nimbus plummeting to fifth, even though they left all the fences standing in the show jumping arena yesterday.

A clear from third-placed Sally Corscadden with her Ballindenisk CIC winner Young Man put the pressure on the two above and Heinz Wehrli was the first to crack, knocking two rails with the mare Shannonvale Bird to drop to ninth.

Despite the removal of her nearest rival, Caroline Bjoerk still had no margin for error and was determined that the Swedish-bred Just Nimbus was not going to make a mistake. The chestnut rubbed a couple but left them in place, but Bjoerk's caution told on the clock and seven time faults meant not first but fifth.

So Corscadden rocketed up the placings from third to take her first ever three-day win and score a first also for Stephanie von Schilcher.

At Hickstead Dermott Lennon was out of luck in yesterday's King George V Gold Cup when a single mistake from Liscalgot denied him a place in the seven-horse jump-off.