Dr. Whichcot and Lord Shaftesbury

It is stated in Mr. Martyn's *Life of the First Lord Shaftesbury*, that Dr. Whichcot was one of Shaftesbury's most constant companions, and preached most of his sermons before him; and that the third Earl of Shaftesbury, the author of the Characteristics, is said to have published a volume of Whichcot's sermons from a manuscript copy of the first Lord Shaftesbury's wife. Can any of your readers give any further information as to the intimacy between Whichcot and Shaftesbury, of which no mention is made in any memoir of Whichcot that I have seen?