[ London Times ]
This newspaper, most correctly known simply as The Times, began publication in 1785 and continues to this day.
The edition of September 22, 1835, carried the following "for sale" notice for a black "Newfoundland Retriever":
TO SPORTSMEN and others. — To be SOLD, a bargain, a remarkably handsome NEWFOUNDLAND RETRIEVER, nearly all black, a very valuable dog, possessing superior qualities; has been greatly and deservedly admired. Price 6 guineas. Apply to Mr. Bennett, solicitor, 8, Bow-lane, city.
That this dog is identified as a 'Newfoundland retriever' is not necessarily an indication it is a mix. Breed classifications and relationships were in flux for much of the 19th Century.