This was a large tract of marshland extending on the north of the City, outside the wall, between Bishopsgate and Cripplegate, described by Fitzstephen in 1170 as the great fen, which waters the walls of the city on the north."
The "mora" outside the postern of Cripplegate is mentioned in the charter of William I. to St. Martin le Grand.
It included part of the old prebendal manor of Finsbury and Halliwell in the parish of St. Leonard SHoreditch, now part of the borough of Finsbury, towards the north and extended to the City ditch on the south, so that it occupied a considerable area.
From the Rotuli Hundredorum, 3 Ed. I. I. 405-6, it appears that this "more or fishery" had always belonged to the community of London until the time of Walter Hervi, the mayor, but in a Patent Roll, 49 H. III. 1265, "La More " is said to have devolved into the king's hands on account of the trespass committed against the king by the Commonalty in the time of the disturbances and war in the land, and was granted by the king to Walter de Merton, prebendary of Haliwell, to form part of his prebend (Cal. P.R. H. III. 1258-66, p.461).
In the City Letter Books are frequent notices of the grant of leases of various parts of the moor for a term of years.
Thus, Thos. Cros, called " de Hakeneye," hired the moor near Bishopsgate of Andrew Horn the Chamberlain for one year, 1319-20 (Cal. L. Bk. E. p. 118).
In 1321-2 the Moor of Haliwell and Vynesbery (appertaining to the Chamber of the Guildhall) was demised by the Mayor and Aldermen for seven years (ib. p.165), and it appears from a note to this record that the Prebendary of Finsbury had previously granted the moor to the Mayor and Commonalty on payment of an annual rent.
A grant was made of the Moor and the keeping of the course of Wallebroke, 48 Ed. III. 1374 (Cal. L. Bk. G. p.324).
Called "le Moremedewe," 21 Ric. II. (Anc. Deeds, B. 2297).
In the 3 H. V. an ordinance enacted that the Moor should be laid out for garden purposes (Cal. L. Bk. I: p.137), and Stow tells us that it was drained and cleansed at this time and that bricks were made there in 1477 (S. 430).
Gardens without Moregate about and beyond the Lordship of Finsbury were destroyed in 1498 and a plain field made for archers to shoot in. It was drained again in 1512, and in 1527 sluices were made to convey the water over the Town ditch to Walbrook and so to the Thames (ib.).
In 1539 "le Moore mede," in the parish of St. Leonard SHoreditch, extending south to the Town ditch, was granted to Sir Martin Bowes (L. and P. H. VIII. XIV. Pt. 1, p.591), being part of the possessions of the lately dissolved Charterhouse.
After this time, the moor being split up into smaller estates and gradually passing into private hands, buildings began rapidly to spring up, streets were laid out, and bit by bit the gardens disappeared and were converted into the houses and offices which now completely occupy the site.
In 1682 Sir Thos. Fitch built over part of Little Moorfields, the houses being erected with an ascent of five steps up to them, the first floor thirteen feet high and coach houses and stables to each house (MSS. Sir H. Verney, H. MSS. Com. 7th Rep. p.480).
The whole district is known as Moorfieldse
A Dictionary of London. Henry A Harben. 1918.