SION-HOUSE, (Middlesex) near the influx of the Brent into the Thames, bet. Brentford and Isleworth, was so called, in remembrance of that Holy-Mount in Jerusalem. It was built by Hen. V. and a house of monks, till he expelled them, and settled 60 nuns here; to whom he added 13 priests, 4 deans, and 8 lay-brethren, so that the whole number might equal that of the 13 apostles, St. Paul being reckoned for one, and 72 disciples of Christ. This house was founded upon a piece of ground in that K's. demesne, which had bel. to the monks, aliens in the manor of Isleworth and p. of Twickenham; and appears by the abuttings and boundings to have been 1938 foot in length, and 925 in breadth. It was one of the first mons. that Hen. VIII. dissolved, because it had harboured the K's enemies. He kept it in his hands, as long as he lived; but Edw. VI. granted it, with the site of the mon. to Edward D. of Somerset, who pulled down the Ch. and began a neat house; but being attainted, the same K. granted it to John Dudley, D. of Northumberland; who being also attainted in the R. of Q. Mary, she restored the nuns hither; who being turned out of it by Q. Eliz. she restored the house to the posterity of the said D. of Somerset, whose attainder she reversed, and his son was made Ld. Beauchamp and E. of Hartford; but the title of D. was not recovered, till the Rest. of Cha. II. Q. Eliz. sometimes resided here, as did the Pss. Ann of Denmark (after she was out of favour with K. Will.) by virtue of a compliment from the old D. of Somerset; whose seat it then was, as it is now of the E. of Northumberland (Hugh Percy, late Sir Hugh Smithson) who married his daughter. It is a noble, square, stone-building, finely finished and furnished. Thomas E. of Derby, who went with Hen. VIII. to meet and accompany the emperor of Germany from Dover, was buried in this mon.