After studying at the Royal Academy of Music, Jay joined the D'Oyly Carte Opera Company in 1897, with whom she began singing principal roles immediately, becoming the company's leading soprano in 1899, where she played leading roles in comic operas including The Rose of Persia, The Pirates of Penzance, Patience, The Emerald Isle and Iolanthe.
[1] On leaving the Academy, in 1897, she joined the D'Oyly Carte Opera Company with a week-long trial at the Savoy Theatre, singing the part of Elsie Maynard in the first London revival of The Yeomen of the Guard.
[2] A reviewer for The Era wrote of her Mabel: "Miss Isabel Jay's bright, alert acting and fascinating personality would have condoned many deficiencies.
But in addition to winning all hearts by her freshness and earnestness, Miss Jay gave us a delightfully easy and accomplished rendering of her share of the score, and the way in which she used a very valuable voice told of sound training and keen intelligence.
"[3] Jay rejoined the main D'Oyly Carte company at the Savoy in 1898, briefly playing Gianetta and then Casilda in The Gondoliers, and soon took over the role of The Plaintiff in Trial by Jury, winning a favourable review in The Sunday Times.
[2] Late in 1899, Vincent left the D'Oyly Carte Opera Company, turning down the secondary role in The Rose of Persia when she was passed over to sing the lead, Sultana Zubeydah, which was given to Ellen Beach Yaw.
[4] Now the company's leading soprano, Jay played Mabel in Pirates (1900), again earning good notices, and the title role in the first London revival of Patience (1901).
[1][2] After the birth of her first daughter, Celia Mitchell Anderson (1903–1997), Jay returned to the stage, taking over the role of Marjory Joy in a hit production of A Country Girl.
For the next four years, she starred regularly in Curzon's West End productions, often at The Prince of Wales Theatre and often in a show written by Paul Rubens.
[1] Jay's health began to deteriorate due to the effects of scarlet fever as a child, and she died at age 47 in Monte Carlo, having been on a cruise with her husband.