British History Online describes it thus:
It is variously described as a manor, a messuage, a district, etc., and was situated at the north-east end of Mark Lane, in the ward of Aldgate.
The earliest notice occurs in a confirmation by Robert de Valonus of the grant made in 1177 by David de Cornhella and Robert his brother to the canons of Holy Trinity of their land of “Blanchesapeltuna,” this land being in the soke of the said Robert.
This description of it as being “in the soke” of Robert de Valonus may account for its apparent alienation from the jurisdiction of the City and for the peculiar privileges it seems to have enjoyed as a manor, such as the holding of manorial courts from time to time by the Earls of Hereford (See Ch. I. p.m. 23 Ed. I. No. 57 ; Cal. Close Rolls 15 Ed.III. 1341-3, p. 244).
It seems to have remained in the possession of the Priory until the 13th century. But in 1288, 16 Ed. I., we find from a Chancery I. p.m. that the messuage and appurtenances called “le Blaunch Appleton” were divided amongst the heirs of John de Vallibus. Later it passed into the possession of the de Bohuns, Earls of Hereford and Essex, and remained in their family until temp. Rich. II. (Anc. Deeds, B. 2030).
After the death of the Countess of Hereford (when the earldom became extinct), 8 Rich. II. (ib. D. 415), the property was divided and passed into the hands of various owners (Cal. P.R. 9 Rich. II. 1385-9, p. 57) and (S. 151).
In 1636-7 the messuage called Blanch Appleton was claimed by the Mayor and Commonalty of the City with a tenement called “Stewards Inn” (L. and P. Chas. I. 1636-7, p. 466).
Basket-makers, wire-drawers, and other foreigners were permitted to have shops in this manor and not elsewhere in the time Edward IV. (S. 151).
The name survived in the 18th century in Blanch Appleton Court (q.v.).
The derivation of the name is obscure.
It’s not named on the 1746 Roque map, but it is shown on the 1578 Agas map as “Blanch Chapelton”.
1 Annotation
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Blanch Appleton, in Aldgate Ward, was on the east side of Mark Lane near Fenchurch Street. Strype, 1720, describes it as "a large open square place, with a passage to it for carts, which is called Blanch Appleton Court, having pretty good timber houses, which are indifferently well inhabited. It hath a turning passage on the south side by an alley which encompasseth some of the houses." The name was derived from the manor of Blanch Appleton, which belonged in the reign of Richard II. to Sir Thomas Roos of Hamelake. It is enumerated (9th of Henry V.) in "The Partition of the Inheritance of Humphrey de Bohun, Earl of Hereford and Essex," under the head of "London—Blaunchappulton." Hall, in his Chronicle (ed. 1548), writes it Blanchechapelton. In Strype's Map, 1720, it is given as Blanch Chaplin Court; the further corruption was into Blind Chapel Court, by which it appears to have been commonly known. The Common Council of London ordered, October 12, 1464, that "basket makers, gold wire-drawers, and other foreigners [i.e. persons not having the freedom of the City] using mysteries within the City, shall not henceforth hold shops within the liberty of the City, but only at Blanch Appulton, so as they might have sufficient dwelling there."
---London, Past and Present. H.B. Wheatley, 1891.