Children with Nanny and Gardener

William Mulready, 1854, Leeds Art Gallery 

this looks like a genre scene, but what is it showing?   a couple of posh children outdoors in the care of the nanny and a gardener?   

the children look as if they belong in a family portrait, or a conversation piece, but missing their parents and pets.   The landscape view and masonry pillar indicate a substantial country house, as also do the adult employees.

is the location generic or verifiable?  to what family does this group belong?  Or is it a scene from literature or drama?

The infant in the nursemaid's arms resembles that in Mulready's Toyseller.   Does the boy's drum invoke the Crimean war?    is this part of a pictorial narrative?

i've been wanting to know more about this painting for years.