He was a son of Arnold St Leger, of Ulcombe, MP for Kent.
[3] He married Margery Danet, daughter and heiress of James Donet (died 1409) of Silham in the parish of Rainham, Kent, by whom he had children including: He died in 1441 and was buried in the chapel of St Thomas the Martyr in the parish church of Ulcombe, as he requested in his will.
His Latin will dated 12 December 1441 survives in the records of the Prerogative Court of Canterbury.
[8] A fragment of his monumental brass survives in Ulcombe Church, now displayed as a mural in the north aisle.
The inscription is lost, but is said to have been: Here lyeth John Seintleger Esquyer, and Margerie his wyfe, sole daughter and heir of James Donnett ...