Glen Shiel is out of Gonfilia (Big Shuffle), winner of the Gr.3 Princess Elizabeth S. and also a stakes winner in France. He is her only pattern winner and a full-brother to the unraced 2-year-old filly Greta Hellstrom, and a half-brother to Signs In The Sand (Cape Cross), placed in the Gr.3 Sirenia S.

Second dam Gonfalon (Slip Anchor) is also the dam of Gonlargo, a full-sibling to Gonfilia, who won the Gr.3 Grosser Preis der Dortmunder Wirtschaft and was second in the Gr.2 German 2000 Guineas.

Third dam Grimpola (Windwurf) won the German 1000 Guineas, then a Group 3. Her descendants include Fame and Glory (Montjeu), a multiple Group 1 winner including the Gr.1 Irish Derby, and Legatissimo (Danehill Dancer), a multiple Group 1 winner including the Gr.1 1000 Guineas.

Gonfilia is related to Gonbarda (Lando), winner of the Gr.1 Deutschland-Preis and the Gr.1 Preis von Europa. Gonbarda is the dam of the sire Farhh (Pivotal), winner of the Gr.1 Champion S. and the Gr.1 Lockinge S., and of Racing History (Pivotal), winner of the Gr.3 Winter Hill S. and second in the Gr.1 Grosser Preis von Bayern.