John Barham Day (1793–1860) was a British jockey and trainer. For much of his career he was usually known simply as John Day; when his son of the same name rose to prominence, the older man was referred to as John Barham Day, John Day, Sr. or Old John Day. A member of a highly successful racing family, Day first made his name as a jockey in the 1820s and rode the winners of sixteen classics before retiring. In the mid-1830s he set up as a trainer of racehorses at Danebury near Stockbridge. He established a reputation as a shrewd and skillful handler of horses and specialised in landing betting coups. Horses trained by Day won seven classics between 1838 and 1854, during which time he was regarded as the leading trainer in the South of England and the main rival of the Yorkshire-based John Scott. He was known as "Honest John", but the sobriquet appears to have been applied ironically.

The Oaks Stakes is a Group 1 flat horse race in Great Britain open to three-year-old fillies. It is run at Epsom Downs over a distance of 1 mile, 4 furlongs and 6 yards, about 1½ miles, and it is scheduled to take place each year in late May or early June. It is the second-oldest of the five Classic races, after the St Leger. Officially the Betfred Oaks, it is also popularly known as simply The Oaks. It has increasingly come to be referred to as the Epsom Oaks in both the UK and overseas countries, although 'Epsom' is not part of the official title of the race.)