"I'm nearly twice as old as some of the others, so I was determined to be fit," 45-year-old Stark said at Stoneleigh, where 11 members of the squad were on a training course. Next month ("on April Fool's Day") he will take a fitness test including so-called "skinfold thickness", assessment of leg and arm strength, and 13 minutes running on a treadmill.
The tests have been introduced to obtain money from the Lottery Sports Fund. Around pounds 90,000 will be available for riders' subsistence, though Stark (who travels to Atlanta today to give lessons) is not eligible because he earns too much from teaching. Upkeep for his two children, both in full-time education, cannot be included because they are over 16.
But Stark benefits from the lottery as one of six British riders having their expenses paid to next month's Lexington Three-Day Event in Kentucky, as are Kristina Gifford, Katie Parker, Owen Moore and Charlotte Ridley.
Mary King, who gave birth to a son last February, is not on the world class list, but is likely to be added once back in competition with her top horses, Star Appeal and King Solomon.
David Robinson, the acting world class performance director, expects in a few weeks to hand to a new director, who has been selected and whose name will be released shortly.
HORSE TRIALS WORLD CLASS PERFORMANCE SQUAD: C Bartle, P Beckett, J Brakewell, K Dixon, A-M Evans, W Fox-Pitt, K Gifford, L Law, O Moore, K Parker, G Parsonage, P Phillipps, C Ridley, I Stark, N Taylor, J Tulloch.