St. James's Park was directly behind Whitehall Palace; Charles II filled it with a formal pattern of onamental water and avenues, including a canal for which the Doge of Venice despatched two gondolas.
In summer, it was fashionable to drink warm milk, freshly drawn from herds of cows placidly grazing in the London parks, at a kind of milk bar provided for the purpose. The milk sellers would advertise their wares by calling: A can of milk, ladies, a can of red cow's milk, sir!
Charles II used to take a daily walk through St. James's Park accompanied by his courtiers and a number of dogs. With the king's long legs and fast pace, Charles and the dogs invariably left the others far behind. Petitioners used to gather in the park, hoping to accost the king on his walk, but he moved so swiftly it was rare that anyone could catch up with him.
(It was on one of Charles's walks through St. James's Park that he was first informed of the supposed "Popish Plot" to murder him, when he was approached by Christopher Kirkby, a chemist employed in the king's laboratory, who told him he was in danger. Charles referred the man to one of his ministers, then carried on with his walk. Though the king gave little credence to it, the plot was taken seriously by several of his ministers and soon the nation was in a panic. By the end of the 1670s, propaganda pamphlets were proclaiming that James I had been murdered, that the Great Rebellion and the death of Charles I had been due to the Jesuits, and that the Great Fire had been set than no other than the Duke of York. At the height of the hysteria, some women such as the Earl of Shaftesbury's wife, were so terrified of being "ravished" by Papists that they carried pistols hidden inside their muffs.)
Hortense Mancini and Anne of Sussex once sneaked out of Whitehall Palace in the middle of the night with swords hidden underneath their nightgowns so they could practice fencing in the park.
St. James's Park by night could be a dangerous place; besides being a lover's rendevous it was also a haunt of prostitutes and the scene of many attacks, including rapes.
A Ramble in St. James's Park by John Wilmot, Earl of Rochester: