With the addition of the seven newcomers at £6,750 each, a total of 122 horses are now engaged in Britain's premier Classic, the nation's richest race with prize-money of £1.125 million for 2021.
Mac Swiney is a 20-1 chance with bookmaking firm Ladbrokes behind 4-1 favourite High Definition. He kept on well in heavy ground to beat One Ruler in a gutsy effort to land the final G1 of the British season at Doncaster and lay down Classic claims for owner-breeder Jim Bolger, who also trained his Derby-winning sire New Approach.
Bolger named the colt after Irish political figure Terence MacSwiney, who died from a 74-day hunger strike in Brixton prison almost 100 years to the day before his namesake landed the G1 event at Doncaster.
One Ruler is one of four Charlie Appleby-trained colts added to the Derby alongside stablemates Adayar, a nine-length winner on his second start at Nottingham, Frankel colt Hurricane Lane and dual winner Yibir, who landed the Haynes, Hanson & Clark Conditions Stakes at Newbury.
The other two additions were Hugo Palmer-trained Irish Legend, unbeaten in two, and Mojo Star (Richard Hannon), beaten a nose on his only outing at Newbury.
A total of 60 entries have also been revealed for the Cazoo Oaks, on Friday June 4, when 31 horses have been engaged for the Coronation Cup. Nine of them are trained by Aidan O'Brien, including shock 2020 Derby winner Serpentine.