The Tyne & Wear Historic Environment Record (Sitelines HER ref. 1241) describes:
The cache of over 5000 Roman coins, known as the Walbottle hoard, was found in 1879 during the construction of the Newcastle and Gateshead Water Company's filter beds (HER ref. 4236). It seems likely that the hoard may have been concealed in the Wall ditch near the site of Milecastle No. 11, at Throckley Bank Top. The coins were mostly of the decade AD 260-70. The hoard was dispersed in small lots by the finder, an Irish labourer, but subsequently some eight hundred or more were acquired by the Society of Antiquaries of Newcastle.
As recorded in HER ref. 4236:
The water treatment works with extensive filter beds were completed in 1875 for the Newcastle and Gateshead Water Company. This involved extensive terracing and excavation of the area of the treatment plant, during the course of which the 'Walbottle Hoard' (SMR 1421) was found.
Clayton, J. (1880). Discovery of a Hoard of Roman Coins on the Wall of Hadrian. Archaeologia Aeliana Series 2. Vol 8, Society of Antiquaries of Newcastle. pp. 256-280.
The vessel in which the.coins were contained is represented in the engraving on the previous page; it is of dark-coloured earthenware, and measures in height one foot two inches, and in girth or circumference at the widest part thirty-six inches.
The paper explains that in AD 270-272 there were disturbances on the frontier that could account for the concealment of the hoard.
Guest, P (2015) 'The Burial, Loss and Recovery of Roman Coin Hoards in Britain and Beyond: past, present and future' pages 101-116 in J. Naylor and R. Bland (eds) 'Hoarding and the Deposition of Metalwork from the Bronze Age to the 20th Century: a British Perspective.' Oxford: Archaeopress.
Guest P. (2018) ‘The Walbottle Hoard of 1879: re-examination and reassessment’, Archaeologia Aeliana 5th series, vol. 46, 41-75 (with F. McIntosh and M. Ponting).
"imagined ‘events’ that led to its owner hiding the jar and coins in the ground, both authors believed, firstly that the 5,000 coins had been buried because of an imminent threat to the owner and presumably his property, secondly that it was the intention of the owner to return at some point in the future to recover his buried wealth, and finally that he had been unable to do so because of some unforeseen incident."