Dame Frances chose Michael Rysbrack, who was one of the leading sculptors of the day, to erect her husband’ s monument. It is in the classical style and faithfully follows Rysbrack’s design. The Agreement was made on the 21 March 1750 and cost £485. The long Latin inscription was composed by Dr William King (1685-1763), principal of St Mary’s Hall, Oxford, ardent Jacobite and friend of Dr Samuel Johnson.
The size of Rysbrack’s monument created a problem; the chancel was small and over crowded. More space had to be found and a Faculty was granted to Dame Frances, in 1753, to add a chapel at the south east end of the church, adjacent to the chancel ‘… to make erect and build a handsome convenient Isle or building… in order to erect monuments seats and pews therein and making a burying vault underneath the same or otherwise to apply the same to Godly purposes’ .The work was carried out in 1755 and is recorded in some detail in the Wynnstay accounts.
Alongside Rysbrack’s monument to the third baronet is a mural tablet to his second son born posthumously. William W.Wynn (b.19 April 1750-d.11 August 1763). It is of great refinement, with oval medallion and sarcophagus in the style of Robert Adam.