[1] In March 2015, Spencer kicked a last-minute penalty as Saracens defeated Exeter Chiefs 23-20 in the final of the Anglo-Welsh Cup.

[2] In May 2016, Spencer was a second-half substitute for Richard Wigglesworth as Sarries defeated Racing 92 to win the European Rugby Champions Cup for the first time.

[6][7] Spencer won his third European Rugby Champions Cup, this time starting the final, as Saracens defeated Leinster.

[14] In October 2024, having previously always played off the bench for England, he was named as a starter for the first time for the autumn nations series fixture against New Zealand.

[15] In January 2025, following injuries to Alex Mitchell and Jack van Poortvliet, he was called into the senior training squad for the 2025 Six Nations.