Sion House stands in the parish of Isleworth, on the Middlesex bank
of the Thames, and opposite Richmond gardens. It is called Sion
from a nunnery of Bridgetines of the same name, originally founded at
Twickenham, by Henry V. in 1414, and removed to this spot in 1432.
This conventual association consisted of sixty nuns, the abbess,
thirteen priests, four deacons, and eight lay brethren; the whole thus
corresponding, in point of number, with the Apostles and seventy-two
disciples of Christ. But the inmates were neither sinless nor spotless;
many irregularities existed in the foundation, and consequently, Sion
was among the first of the larger monastic institutions suppressed by
Henry VIII. The estimated yearly value was 1,944 l. 11 s. 8-1/2 d.,
now worth 38,891 l. 14 s. 2d.

After the dissolution of this convent, in 1532, it continued in the
crown during the remainder of Henry's reign; and the King confined here
his unfortunate Queen, Catherine Howard, from November 14, 1541, to
February 10, 1542, being three days before her execution. Edward VI.
granted it to his uncle, the Duke of Somerset, who, in 1547, began to
build this spacious structure, and finished the shell of it nearly as it
now remains. The house is a majestic edifice of white stone, built in a
quadrangular form, with a flat and embattled roof, with a square turret
at each of the outward angles. In the centre is an enclosed area, now
laid out as a flower garden. The gardens were originally enclosed by
high walls before the east and west fronts, so as to exclude all
prospect; but the Protector, to remedy this inconvenience, built a high
terrace in the angle between the walls of the two gardens. After his
execution, in 1552, Sion was forfeited; and the house, which was given
to John, Duke of Northumberland, then became the residence of his son,
Lord Guildford Dudley, and of his daughter-in-law, the unfortunate Lady
Jane Grey, who resided at this place when the Duke of Northumberland and