[3] She was descended from the British broodmare Shellshock who was a half-sister to Dibidale and to the dam of Tony Bin[4] On 7 June Glass Slippers made her debut in a five furlong maiden race at Haydock Park for which she started a 50/1 outsider and finished third to Angel's Hideaway, beaten four and a quarter lengths by the winner.

[5] On 1 September Glass Slippers started at 3/1 for a more competitive race over six furlongs at Chester Racecourse and won "a shade comfortably" by a neck from Light My Fire after going to the front in the last 75 yards.

[6] Three weeks later the filly was stepped up in class for the Group 3 Firth of Clyde Stakes on heavy ground at Ayr Racecourse and finished sixth to Queen of Bermuda after tiring in the closing stages.

Glass Slippers made no impact on her first appearance of 2019 as she trailed home fifteenth of the sixteen runners behind Dandhu in the Fred Darling Stakes at Newbury on 13 April after losing both of her front shoes in the race.

After four consecutive defeats in Britain, Glass Slippers was sent to France to contest the Listed Prix Moonlight Cloud over 1200 metres at Deauville Racecourse on 4 August and started a 10/1 outsider in an eight-runner field.

Glass Slippers started slowly and looked outpaced in the early stages before beginning to make headway in the last 300 metres and overtook Shades of Blue (another British-trained three-year-old filly) in the final strides to win by a short neck.

"[11] The flat racing season in Britain and Ireland was restructured as a result of the COVID-19 outbreak and Glass Slippers made her first appearance of the year in the King's Stand Stakes which was run behind closed doors at Royal Ascot on 16 June.

In the King George Stakes at Goodwood she overcame a poor start to move into second place approaching the final furlong but never looked likely to threaten the leader Baattaash and was beaten two and a quarter lengths.

[14] For her final run of the year, the filly was sent to the United States to contest the Breeders' Cup Turf Sprint (a race which had never been won by a European-trained horse) over five and a half furlongs at Keeneland on 7 November.

Glass Slippers raced towards the rear before moving up along the inside rail on the final turn and then "squeezed through" a narrow gap between her opponents (hampering Imprimis as she did so) to take the lead in the last 100 yards and win by half a length from Wet Your Whistle.