The pair were responsible for the 1995 winner Sergeyev, who like Andreyev represented a partnership of owners Jonathan Palmer-Brown and Brian Stewart- Brown.
They now plan a repeat assault on 18 June after the three-year-old's win in the pounds 16,250- contest run over the Jersey Stakes trip of seven furlongs.
Hughes, lanky by weighing room standards, sat tall in his seat as Andreyev tracked the pace set by Paul Kelleway's Royal Aty.
Unleashed with a run passing the furlong marker, he stretched out to beat the Kelleway runner by three-quarters of a length.
Two lengths adrift in third came Granny's Pet, with John Dunlop's Shawaf a disappointing 6-4 favourite in fifth.
"Royal Ascot here we come," Hannon's assistant, Sylvester Kirk, said. "Even I can work that one out without looking at the entries.
"The plan is for the Jersey at the moment and the way he has done that he would have to take his chance. He has picked up really well and the ground here is ideal for him it was perfect today."
Apprentice Royston Ffrench, who had the biggest win of his career aboard Inchcailloch in the Cesarewitch here in October, rode his second double and his first on turf courtesy of Welton Arsenal and Janglynyve.
Welton Arsenal initiated the pair, whose combined odds were 53-1, in the NGK Spark Plugs Rated Handicap to give Bridgwater trainer Kevin Bishop his first winner from his first runner at the track.
An unlucky fourth in the Jubilee Handicap at Kempton earlier in the month, Welton Arsenal also has Royal Ascot on his agenda, Bishop earmarking the Royal Hunt Cup.
Ffrench, who is attached to Luca Cumani's stable, rode his 12th winner of 1997 and his 27th in all aboard Janglynyve in the Equity Financial Collections Claiming Stakes, Sean Woods' chestnut defeating Soura by five lengths.
Mark Flower celebrated his first victory on the Rowley Mile when Soojama and Gary Hind took the Equity Financial Collections Handicap by seven lengths from Sea Freedom.
"He's no star but he is honest and I wish I had a stable full of horses like him," was the winning trainer's post-race assessment.
Godolphin's Bold Demand would almost certainly have started favourite for the Ashley Maiden Stakes, but like the Dubians' Swiss Law and Shuhrah was declared a non-runner as Crisford & Co scratch their heads in an effort to find out what has been going wrong with Saeed bin Suroor's horses.
The race went to Assured Gamble, who made all to justify 11-8 favouritism.