The matter of the meal has sometimes seemed as important as the music for devotees of country house opera, as this style of lavish summer entertainment has long been described, initially in a pejorative way.

And why not? Lovers of the good things in life, among which opera emphatically is one, will recognise food and drink to be others. So, too, are swish clothes and elegant motor cars, both seen in good measure where opera buffs gather.

Glyndebourne set the trend for fine dining – whether indoors or out – and was followed by those other ‘G’s of Garsington, Grange Park Opera and the Grange Festival.

When Garsington first gave Benjamin Britten’s The Turn of the Screw in 1992 (with librettist Myfanwy Piper in the audience) our ‘indoors’ was the manor’s barn.

In my carefully preserved programme, festival founder (and manor owner) Leonard Ingrams reveals that this was soon to be lined with panelling from Glyndebourne’s old theatre to make it less draughty.

He writes, too, of the festival’s progress from two nights and one production in its first year to 10 nights with three shows in its fourth. “Where will it end?” he asks.

Leonard, who died in 2005, could hardly have guessed at the 39 nights with six productions of this 30th year, or of the wonders of Mark Getty’s Wormsley Estate where these are seen (since 2011).

Exquisitely tended in the way that only billionaires can arrange, this richly wooded demesne nestling in the Chilterns offers glorious vistas to visitors while they eat.

Many bring their own picnics to enjoy beside the lake, with black swans bobbing on its surface and a herd of deer grazing beyond. Others book a table in one of the elegant tents farther back from the lake or overlooking the fabled cricket ground (whose grass looks too perfect to be real but is) and await the arrival of a picnic from caterers Feasts and the staff to serve it.

The summer picnic (£39.50) offers mushroom. and tarragon paté, smoked chicken salad and banoffee pot, mineral water, coffee and truffles.

The gourmet picnic (£59.50) features potted crab of rabbit sausage roll, followed by rare beef fillet or smoked salmon and prawn salads, and mango and passion fruit mousse.

The summer staples of lobster mayonnaise and strawberries and cream are missing from these menus, I notice, and from the one served in the elegant Long Room Restaurant overlooking the cricket ground. Understandable, I suppose, for picnickers can easily bring their own. What is wanted are dishes that people can’t, or won’t, do for themselves.

These are imaginatively supplied by Feasts under the guidance of Michael North, owner and chef at the Michelin-starred Nut Tree at Murcott. His involvement presumably arises from his association with Garsington’s catering consultant, the Prince of Wales’s former chef Chris Barber, for whom he worked early in his career.

After fending for ourselves with picnics on three visits to Wormsley this season, Rosemarie and I decided on the lug-free luxury (though picnics can be portered) of a restaurant meal for our fourth.

We were surprised to find the tent (essentially what it is on a grand scale) barely half full last Thursday in the interval of (the sensational) Turn of the Screw. But after some dismal weeks, this glorious night was at last one for eating outdoors.

Shadows were slanting across the cricket pitch as we had a first taste of our buttery burgundy (Auxey-Duresses, Benjamin Leroux, 2017, £72) and the starters that it so well suited. Mine was a prettily presented plate of gin-cured salmon, adventurously teamed with black treacle and buttermilk crumb, while Rosemarie had a substantial chunk of powerfully flavoured smoked eel, with beetroot salad and apple purée. She loved it.

She continued with a square of succulent pork belly, the crackling properly crunchy, with celeriac purée, tenderstem, apple and pork jus, while I had equally delicious free-range roast chicken – confit-like in its slight stickiness and rich flavour – with asparagus, wild garlic and chestnut mushrooms.

Pear tTatin and English cheeses (Dorset blue the tops) completed the meal – a treat in all respects and a credit to its suppliers.