The caption said, 'Following the fire at Clandon Park, I've found a few more photos in old albums. Presumably this was destroyed.'
For more about the fire, see Clandon Park House fire: Investigation 'will take time' [bbc.com/news]. For more about the painting, see nationaltrustcollections.org.uk/object/1441467, where we learn
The Hon. Edward Onslow (1758-1829), John FitzWilliam, 8th Viscount FitzWilliam (1752–1830) and George Augustus Herbert, 11th Earl of Pembroke (1759-1827) playing chess; Daniel Gardner (Kendal 1750 – London 1805).
For more about the artist, see Daniel Gardner [Wikipedia].