'I was glad' (Latin incipit: Laetatus sum) is an English text drawn from selected verses of Psalm 122.
It has been used at Westminster Abbey in the coronation ceremonies of British monarchs since those of King Charles I in 1626.
[1] The text accompanies the monarch's entrance into Westminster Abbey and was formalised in the 1662 Book of Common Prayer.
Since the coronation of King James II in 1685[2] an additional non-biblical text is added to the psalm verses used in the Westminster Abbey ceremonies, i.e. the acclamation "Vivat Rex ... " or "Vivat Regina ... " ("Long live King/Queen ...").
The traditional English pronunciation when referring to the British monarch is /ˈvaɪvæt rɪˈdʒaɪnə/ VY-vat rij-EYE-nə.