Author Dona Landry ( her book Noble brutes: how Eastern horses transformed English culture ) says about Mackomilia's image in this print that this 'horse displays natural impulsion and proud self-carriage' and that black groom depicted here is a 'symbol of social status' in England (page 46) and I would add whole Christian Europe of XVII century.
Finally in an letter dated January 22, 1690 from one English gentleman to another we find a description of a Turkish horse:
Sir Christopher Musgrave to Rouert Harley.
''The Turkish horse is valued at 130 luidores. Ten years old, unstrained, his limbs very clean and in a fine condition. His height is fifteen hands wanting one inch.''
Some thoughts on horse and horse breeds by William Cavendish:
With respect to the Northern horses, I have seen some beautiful in their kind, genteel in all sorts of paces, and which have excelled all others in leaping. Moreover, they have a peculiar excellency' in the motion of their fore-legs, which is the principal grace in the action of a horse; but they sooner come to decay than a Barb, and you will always find among them more horses fit for the cart than the manage.
The best stallion is a well-chosen Barb or a beautiful Spanish horse. Some people pretend that a Barb or genet produces too small a breed. There is no fear of having too small horses in England, since the moisture of the climate and the fatness of the land rather produce horses too large. In the choice of breeding mares, I would advise you to take either a well-shaped Spanish one, or a Neapolitan. When these are not easily obtained, then a beautiful English mare, of a good colour and well marked."