It is a row that the scion of one of Britain’s oldest aristocratic families could rather do without as he carves out a career promoting his green credentials.

And, gallingly for the Percy dynasty (one of whose ancestors was the inspiration for Blackadder’s half-witted sidekick, Lord Percy) much of it has been self-inflicted. In the one camp is Earl Percy, friend to Wills and Kate and owner of Syon House, a historic Grade-I listed pile in west London where Henry VIII’s body once lay in state.

In the other camp are the 40 or so disgruntled members of the Park Road Allotments Association in Isleworth who have been ordered to vacate their plots on land adjacent to the stately home, having seen off a bid by the earl and his father, the Duke of Northumberland, to turn it into flats.

The fact that the land was leased to the local authority in 1917 by a previous duke, to grow vegetables for the war effort, has added piquancy to a dispute that has been simmering since the family reclaimed control of it from Hounslow Council in 2015.

Facebook Twitter Pinterest Syon House in west London, one of the ancestral homes of the Percy family. Photograph: Maurice Savage/Alamy

In hand-delivered letters, Northumberland Estates, the management company that oversees the interests of the Percy family, informed the allotment holders that they must vacate their plots by the end of March next year. “We thought we were out of the woods and then we were all served with notice to quit, which seemed somewhat spiteful,” said Annie Aloysius, secretary of the association. “There is a suspicion that they will leave [the land] fallow and then put in another application. They’ve been trying to wear us down but we’re not going without a fight.”

Their bellicose response has triggered headlines about a peasants’ revolt, which threaten to embarrass the 34-year-old earl, who is the founder of a green energy company, Hotspur Geothermal. The company’s website explains its mission is to “benefit local communities through employment, positive social impact, and the development of new and sustainable businesses”.

However, for the earl’s father, the Duke of Northumberland, a close friend of Prince Charles who takes a keen interest in environmental matters, planning problems are nothing new. Proposals to develop an elf-themed playground next to the Percy ancestral home, Alnwick Castle in Northumberland, famous as Hogwarts in the Harry Potter film franchise, have met with resistance from some local councillors.

The redevelopment of the Park Road allotments would have seen the construction of eight blocks of flats, the rent from which would have gone towards the upkeep of Syon House, which Northumberland Estates said needs major restoration work costing almost £19m. This is partly thanks to an ill-fated makeover given to the home by a previous occupant. In the 1830s, the third Duke of Northumberland had its facade re-faced with Bath stone held in place by iron cramps that have now rusted and caused the stonework to disintegrate. Lying under the flightpath to the north runway of Heathrow airport, there are concerns that aircraft emissions are contributing to the decay of the ironwork.

Rory Wilson, CEO at Northumberland Estates, said that even though planning had been refused, “difficult decisions” had to be taken if it was to preserve Syon House, Alnwick Castle and the 120 other listed monuments under its ownership. “Options are very limited at Syon, and the former allotments site, which was underused and overgrown when it came back to us from the council, will be required for alternative use. Northumberland Estates has to remain a viable entity if it is to carry out its heritage obligations, maintain and create employment opportunities and play its role in supporting the rural economy.”

Facebook Twitter Pinterest The Duke and Duchess of Northumberland. Photograph: WPA/Getty Images

This claim was rejected by Tim Rugg, an allotment holder for more than 15 years. “When they took it back under management from the council, they said ‘We’ll manage it better’, but they’ve done nothing of the sort. They haven’t filled any vacant plots, they’ve really run it down.” Rugg described the land as a haven. “When you look at it, it’s almost a bit of a wilderness. There must be 20 different types of apple tree, there are newts in the pond, a bat corridor. From a wildlife flora and fauna point of view it’s quite unique.”

Christine Diwell, secretary of the Isleworth Society, said it would watch what Northumberland Estates did next closely. “The allotments are the remnant of the last market gardens in the area. Given that so many flats are going up, the need for allotments will only increase rather than decrease.”