Florence Coulston Gardner (1853-1934) married William Onslow, 4th Earl of Onslow in 1875. He was a politician and Governor of New Zealand from 1889-1892. The building is Clandon Park House in Surrey, which burned down in 2015. The birds are Tui, from New Zealand, looking longingly at a drawing of Wellington Harbour, probably from the old Government House on Bowen Street, now the site of the 'Beehive', the executive wing of Parliament (but I am just guessing). The quotation is from the Rubaiyat of Omar Khayyam.
Bookplate (click to enlarge)