The Music Party at Melton Constable
Painted by John Theodore Heins
Norfolk Portraits, Vol 2, page 19. Heins is also in the picture with the Astley family and friends. He is standing in green next to the chair and looking towards the dexter (his right).
According to Groves Dictionary of Music, the flute player (in front of mirror) is the composer/oboist/flautist/teacher John Frederick Ranish (1692?-1777).
I understand that the original of this picture is now in the care of the National Trust and can be seen at Seaton Delaval Hall, Northumberland.