In temperament it is gentle, affectionate and playful, quieter than many toy breeds, and can be reserved with strangers. It is usually calm indoors and attaches closely to those it lives with.
It is compact and cobby, with a domed head, a short upturned nose, large dark eyes set wide apart and long, low-set ears covered in heavy feathering. The coat is long, silky and straight or slightly wavy, with fringes on the ears, chest, legs and feet. Many Blenheims carry a red spot on the crown, known as the lozenge.
The English Toy Spaniel's present form was fixed by Victorian breeders, who prized an ever shorter face and rounder head over the flatter-skulled toy spaniels of earlier portraits. Its colours were given names of their own: black and tan dogs were called King Charles, tricolours Prince Charles, solid red dogs Ruby, and red and white dogs Blenheim, after the Dukes of Marlborough's seat at Blenheim Palace. In the United States the breed is shown in two colour-based varieties. The breed has chiefly been a companion rather than a worker, kept as a lapdog in households and courts.