Under Queen Mary he had the honour of arranging the music for the formal restoration of Catholicism at St. Paul's, in November 1553.
Under Elizabeth I, in 1559, Westcott refused to subscribe to the Thirty-Nine Articles, yet official documents from 1559 to 1561 prove that "Master Sebastian" was well paid for his musical and dramatic performances.
In May 1561 the Catholic propagandist Nicholas Sander, in a report to Cardinal Morone, highly praised Westcott.
[1] 14 years later, in December 1577, Westcott was deprived by Bishop John Aylmer and imprisoned in the Marshalsea as a recusant.
Apparently, Queen Elizabeth missed her customary Christmas plays by the choristers of St. Paul's, and so Westcott was released on 19 March 1578.