Private Gary, the 11-year-old brown gelding who won last week's Rokeby Challenge Bowl in a walkover in Upperville, Va., had a much more difficult time earning the victory today in the 42nd running of the Howard County Cup.

Ridden by D.M. (Speedy) Smithwick Jr. of Middleburg, Va., the Donna Truslow-trained gelding led for most of the 18 fences over three miles but had a hard time holding the lead.

Irish-bred Cervo, a 7-year-old bay gelding ridden by Joey Gillet, was on top by four lengths over the final fence before Smithwick went to his riding crop and urged the 1983 Virginia Gold Cup winner over the finish to win by a nose.

"I thought we would be making the run by Cervo a little bit easier than we did. I had dead aim on him at the last fence," Smithwick, 25, said. "But Private Gary has a helluva stretch run in him." Private Gary was timed at 6:11 2/5. Six lengths back in third was Arch Revolt, ridden by David Benson.

Peter S. Thompson, a retired investment banker living in Easton, Md., is still making his investments pay off. On Friday he flew in 25-year-old rider Paul Webber from Oxfordshire, England, and saddled him on two of his horses, Priest's Rock in a split division of the Alda Clark Challenge Plate and A Breezy Spray in the mile-and-a-quarter Meriwether flat race. Each horse won by a nose.