The UK system of prime lamb production relies heavily on prime lambs bred out of Mule ewes – but the Mule ewe is actually a cross-bred and although she can be bred from a wide range of pure-bred ewes the sire is always the Bluefaced Leicester.

The Bluefaced Leicester is, without doubt, the most influential sheep breed in the UK because of its important role as the sire of the millions of Mule ewes that form the foundation of the UK prime lamb industry.

The breed was developed over 200 years ago. There are around 1200 flocks in the UK but apart from maintaining a pure-bred gene pool, the prime purpose of these flocks is to produce rams that can be put on to native-breed ewes to produce a “Mule”.

The Blue-faced Leicester is crossed with almost 40 different UK ewe breeds to create a wide range of Mule ewes but the most well known are the North of England Mule (bred from the Swaledale), the Welsh Mule (bred from the Welsh Mountain or Beulah), and the Scotch Mule (bred from the Scottish Blackface.) There are also breeds such as the Exmoor Mule (bred from the Exmoor Horn) and the Cheviot Mule (bred from North and South Country Cheviots).

The Bluefaced Leicester's unique role in the UK sheep industry has been built on its ability to pass on specific traits to its female progeny. These traits are primarily prolificacy and milking ability.

Bluefaced Leicester rams are bought in large numbers every autumn by hill flockmasters who run them with their own native-breed flocks and then sell the female “Mule” progeny – usually as gimmer lambs - to lowland farmers. These Mules are then crossed with terminal sire breeds – such as the Suffolk , Texel and Charollais – to produce prime lambs.

Mule ewes sired by Blue-faced Leicester rams are not only renowned for the number of lambs they produce (200%) and their milking ability and mothering ability, but also their ease of management.

In the UK large flocks of Mule ewes can be managed with less labour than other breeds. Mule ewes now make up half the UK 's national ewe flock.

The Bluefaced Leicester is an unusual looking sheep. It has a broad muzzle, distinctive head with Roman nose and long erect ears. The colour of the skin on the head should be blue showing through white hair. The breed has a long neck, broad shoulders, good hindquarters and should be deep through the body. The wool is tightly purled (curled) and is among the most valuable wool produced by any UK sheep breed.

The Bluefaced Leicester Sheep Breeders Association which undertakes a sire reference scheme to identify superior sires to ensure that the breed's essential breeding traits and conformation are maintained.

The Bluefaced Leicester's ability to produce outstanding breeding females from a wide range of different ewes has been proved time and again in the UK where its influence as the mainstay of the commercial sheep sector is as strong as ever. No other breed has ever come close to challenging the dominance of the Bluefaced Leicester as the ultimate sire of commercial breeding ewes that are prolific, milky and easily managed.