For filming to be a positive experience, you as the owner need to be clear about what the crew can and cannot do and where they have access, warns the Countess of Carnarvon. The rule at Highclere is that the crew never touches anything; if a piece of furniture or a painting needs to be moved it must be done by the Countess’s staff – Ellis suspects this is because of an incident on the inaugural day of filming Downton, when a turquoise chest belonging to the Countess was knocked onto the floor and broken. “It turned out to be one of her prized possessions and had to be sent to Sotheby’s for repair,” he recalls…

All breakages and damage are, of course, covered by the film crew’s insurance but Ellis dreads owning up. “It’s a tense, high-pressure situation but we talk it through, I never bluff, I apologise and we get it sorted out.” He remembers a crew member at a different stately location enthusiastically stapling blackout curtains to 15th-century beams, costing the film crew £15 per staple in repair bills, and another occasion where a crew security guard knocked a piece of timber through an oil painting. “Would I let a film crew in my house? Never,” he laughs.