Sheep of this kind, little different from the modern breed, were shown in paintings from about 1760 at Tabley House in Cheshire, and – by George Stubbs – at Wentworth Woodhouse in Yorkshire.

[5]: 77 In the de Tabley family, the tradition was that the piebald sheep had come ashore in Ireland from a wrecked ship of the Spanish Armada in 1588, and been brought to England by Sir John Byrne on his marriage.

[9] In 2009, a study which used endogenous retrovirus markers to investigate the history of sheep domestication found the Jacob to be more closely linked to sheep from Africa and South-west Asia than to other British breeds,[4]: 4  though all domestic breeds can be traced back to an origin in the Fertile Crescent.

[10] Some believe that the modern breed is actually the same one mentioned in the Bible (although there is little genetic evidence) having accompanied the westward expansion of human civilisation through Northern Africa, Sicily, Spain and eventually England.

[11] Elisha Gootwine, a sheep expert at the Israeli Agriculture Ministry, says that the resemblance of a British breed to the Bible story is a coincidence, that the breed was not indigenous to ancient Israel, and that "Jacob Sheep are related to Jacob the same as the American Indians are related to India".

[13] Mary Cavendish, dowager Duchess of Devonshire, who had a flock of Jacob sheep at Chatsworth House in Derbyshire, was the first president of the society.

[16] The Jacob was introduced to Israel in 2016, when a small flock of about 120 head was shipped there from Canada[17][18][19][20][21] by a couple who believed the breed is the same one mentioned in Genesis.

[10] In 2012 the total Jacob population in the UK was reported to the DAD-IS database of the FAO as 5638, of which 2349 were registered breeding ewes.

Jacob owners do not usually dock the tail completely, even for market sheep, but instead leave several inches (several centimetres) to cover the anus and vulva.

They provide a lean carcass with little external fat, with a high yield of meat compared to more improved breeds.

Ideally, horns are smooth and balanced, strongly attached to the skull, and grow in a way that does not impede the animal's sight or grazing abilities.

Partial or deformed horns that are not firmly attached to the skull, often referred to as "scurs", are not unusual but are considered undesirable.

Desirable colour traits include an animal which is approximately 60% white, with the remaining 40% consisting of a random pattern of black or "lilac" (brownish-gray)[7] spots or patches.

[26] In addition to these markings, random spots may occur on the rest of the body and legs (including the carpi, hocks, and pasterns).

The condition known as split eyelid is a congenital defect common to several polycerate British breeds, and is genetically linked to the multi-horned trait.

[25][29] In 1994, an unusual form of asymmetric occipital condylar dysplasia was found in two Jacob lambs; a possible link to the multi-horn trait has been suggested.

[34] In 2022, two babies diagnosed with the disease were treated with gene therapy developed from this research and further follow up studies are being conducted.

In contrast, the British Jacob has been selected for greater productivity of meat, and therefore tends to be larger, heavier and have a more uniform appearance.

[7] Jacobs are typically hardy, low-maintenance animals with a naturally high resistance to parasites and hoof problems.

[36][37] Due to their low tail dock and generally unimproved anatomy, Jacob ewes are widely reputed to be easy-lambing.

The wool is medium to coarse: staple length is about 8–15 cm (3–6 in) and fibre diameter about 32–34 microns (Bradford count 48s–56s).

[43] The colours may be separated or blended after shearing and before spinning to produce various shades of yarn from a single fleece, from nearly white to nearly black.