Two words in faded brown ink on the back of a translation of Homer’s Odyssey have linked the 18th century poet Alexander Pope to the design of a grand garden created for one of his best friends, Henrietta Howard, a mistress of George II.

Emily Parker, a landscape historian, said the words “Plum Bush” jumped off the page at her as she pored over Pope’s manuscripts in the British Library, looking for proof that he had indeed designed one of the great lost gardens of Georgian England.

Parker is landscape adviser to English Heritage, which now cares for Marble Hill house and its grounds by the Thames in west London.

Marble Hill. Photograph: Phil Ripley/English Heritage

“Pope re-used old sheets of paper when he was working on his translation, and it was known there were garden designs on the back of some pages. It was believed these related to Henrietta Howard’s garden at Marble Hill, on which he was known to have advised, but there was no definitive proof linking the designs and her garden.

“But when I spotted the words Plum Bush, which other researchers seem to have overlooked or missed the significance of, I was astonished. I recognised the words immediately. Plum Bush was the old field name for a small part of her estate. This is the first solid proof linking Pope with the garden as it was executed.”

Parker’s discovery is further ammunition for English Heritage plans to partially recreate the lost garden, which met with such fierce opposition last year from some local residents, including a 4,000-signature petition, that the conservation charity withdrew its planning application.

A plan for the garden at Marble Hill attributed to Alexander Pope, drawn in about 1724. Photograph: Norfolk Record Office

Those opposing the scheme included almost all the residents of Montpellier Row, a magnificent terrace of listed early 18th century houses bordering the park, who argued that English Heritage was proposing major changes based on spurious evidence.

Pope’s warm friendship with Henrietta Howard was well known, and his letters record an arrangement to meet at Marble Hill with the celebrated garden designer Charles Bridgeman, but many had doubted whether the elaborate plans for the garden were ever carried out.

English Heritage experts say, however, that a recent excavation by Historic England has revealed many features matching a map of the garden discovered among the Howard papers in Norfolk’s county records, including a grotto and meandering paths intended to recall the shady groves of classical literature. The archaeologists also found the foundations of a rare nine-pin bowling alley also dating from the 18th century.

George II seems to have taken Henrietta Howard as a mistress because he felt he was entitled to one rather than from grand passion. When she escaped with a royal pension from both the court and her drunken spendthrift first husband, she bought the land by the river, built her pretty white villa in the fashionable Palladian style and settled down happily with a circle of intellectual friends including Pope, who lived a few miles further upstream.

A plan of Marble Hill showing how the garden was laid out in about 1749. Photograph: Norfolk Record Office

Pope’s translations of the Iliad, which Samuel Johnson called the greatest translation in any language – and then the Odyssey – made him famous, and established his own reputation as a poet.

His own much more modest garden was also renowned, including an elaborate grotto. The house was demolished in the early 19th century – to the fury of admirers including JMW Turner, who painted its wreckage – but the grotto still survives under the road and 20th century buildings.

A previous generation of local residents saved Marble Hill house and grounds when the shipping family Cunard put it up for sale for development in 1898. The outcry forced the abandonment of the sale, and instead it became a London county council public park. English Heritage took over in 1986.

It has undertaken a major bridge building consultation effort to try and win approval for its Heritage Lottery-funded Marble Hill Revived project involving major restoration work on the house, partial recreation of the lost garden and an expanded cafe.

The house, currently charging and open only at weekends, would become free admission, and most of the grounds would remain as they are today, open to footballers, picnickers and dog walkers.