From Historic England entry:
“ROYAL BOTANIC GARDENS KEW Cumberland Gate
(Formerly listed as Cumberland Gate, ROYAL BOTANIC GARDENS)
II Mid C19. Cast-iron, elaborate scroll design in three arched panels with overthrow carrying Lion and Unicorn Crest. Gatepiers red and yellow brick. Victoria gates identical ironwork.”
From the London Borough of Richmond upon Thames’s CONSERVATION AREA STUDY – KEW ROAD NO.55, KEW GARDENS NO. 15 & LAWN CRESCENT NO. 20:
“Arrival of the Railway
The railway arrived in 1869, following the completion of the bridge over the Thames in 1868. Originally it was operated by the London and South Western Railway and later the District Line Underground. Joseph Hooker, director of the Botanic Gardens, wanted the station to be sited opposite the Temperate House so he lowered the wall at this point in preparation. The LSWR unexpectedly built it 600 yards to the north (which actually served the residents of Kew better, who were at that time clustered around the Green) but the gap in the wall in line where it would have gone still remains. The station was ‘in the middle of nowhere’, at the edge of the Leyborne-Popham market gardens, and the only road near the station was Sandy Lane (renamed Sandycombe Lane in 1884) incorporating Broomfield Road.
Another public entrance to the Gardens was required, and this was provided by John Gardner Dillman Engleheart, a local estate owner, who financed the building of the gate and Kew Gardens Road.The entrance is known as Cumberland Gate, after earlier residents of Kew, the Dukes of Cumberland.
The number of public visitors to the Gardens increased from 28,000 in 1845 to 1,244,000 in 1883, thanks largely to the railway; and many of those who came as visitors sought residences in the area. The two large landowners, the Selwyns and the Englehearts, had anticipated this demand and were already building houses on their estates.
…Engleheart was responsible for the houses on the southern end of Kew Road, including Sheendale Road, and a long line of houses on the east side of Kew Road. He was developing Kew Gardens Road in the early 1880s. The area remained fashionable and early residents included a number of artists and photographers.”
From Royal Botanic Gardens Kew World Heritage Site Management Plan 2019-2025:
“…Cumberland Gate – this smaller gate on Kew Road, also built in 1868, unintentionally became the closest gate to the new station, and remained so until the Victoria Gate was opened in 1889. The Cumberland Gate is no longer in regular use but remains as an opening in the Kew Road wall, through which views into and out of the garden are obtainable through the wrought iron gates…”