Description:
No longer extant, this monument apparently took the form of a representation of three goddesses, possibly the Three Graces. (according to Leach and Pacey’s publication).
The fragment which survives, is of Portland stone and described as a serpentine fluted sarcophagus in relief with pediment and acroteria.    The sarcophagus rests on devices of dolphin heads and spheres, and there are further dolphins and a shell within the tympanum.   The chest is ornamented with Corinthian quarter columns with classical faces to the upper corners.   The frieze has sea monsters carved, and on the side is a relief of the Three Graces.

History:
The monument still existed in 1898, but by 1909 it had been destroyed by vandals.
When Manby Hall was demolished the remains of the monument were moved to the wood-yard at Broughton,  where they remained until at least 1950.  A fragment of the monument still survives at Brocklesby Park, Lincolnshire.
The monument was carved by Richard Hayward (1728-1800) in 1788.

Inscription:

To the memory of the great and celebrated navigator, Captain Cook

GPS Coordinates:  53.566094,  -0.549557

References:
Cook’s Log, page 3, vol. 40, no. 1 (2017)
Cook’s Log, page 31, vol. 40, no. 2 (2017)
Cook’s Log, page 58, vol.4 3, no. 2 (2020)
Yorkshire Post & Leeds Intelligencer, 21 July, 1928. p.16.
Yorkshire Post & Leeds Intelligencer, 11 July, 1933.
Book: Leach, Terence R., & Pacey, Robert. Lost Lincolnshire Country Houses.  Society for Lincolnshire History and Archaeology.  1992. Volume 2.
Book: Lord, John. “Richard Hayward:  An early and some later Commissions” in Church Monuments, the Journal of the Church Monuments Society.  1997.  Vol. XII.
Website:   http://memorials.rmg.co.uk/m1675/