Who stated that Sir Charles’s health had been bad for some time?

Sir Charles' servants, several friends, and his doctor (Dr. James Mortimer), all testified to Sir Charles' deteriorating health.

"Sir Charles was a widower, and a man who may be said to have been in some ways of an eccentric habit of mind. In spite of his considerable wealth he was simple in his personal tastes, and his indoor servants at Baskerville Hall consisted of a married couple named Barrymore, the husband acting as butler and the wife as housekeeper. Their evidence, corroborated by that of several friends, tends to show that Sir Charles’s health has for some time been impaired, and points especially to some affection of the heart, manifesting itself in changes of colour, breathlessness, and acute attacks of nervous depression. Dr. James Mortimer, the friend and medical attendant of the deceased, has given evidence to the same effect."