The topic is often raised, that the modern Clumber is the same or better then the originals, but without reference to illustrations; here are some of the very early illustrations of Clumbers for you to consider this statement. There are a lot more examples of very early Clumbers in my book The White Spaniel.
1784
(before Clumbers at Clumber Park) image is from the insert in The White Spaniel, “as commissioned by Charles Anderson-Pelham, 1st Baron Yarborough of Brocklesby Park in Lincolnshire.”
1788
First is part of an ENGRAVING taken from the first known painting of the breed at Clumber Park, so there are two levels of interpretation here, the artist’s and the engravers, I am including it it because it is a good size reproduction.
Here is a photo of the painting owned by Sheffield Gallery, which sadly at the time of writing is not on public view
By Francis Wheatley [Public domain], via Wikimedia Commons
1810 (guess)