Nobody does the tension between the old and the nouveau better than the British. Ask Charles Maurice Petty-Fitzmaurice, 9th Marquess of Lansdowne, a man struggling to make ends meet by opening his Wiltshire home and gardens to the paying public. He may own the sixth most visited private house in Britain but his isn’t the easiest of lives. Acquired by his family in 1754, the Bowood House estate is now a third of the size and making the whole thing viable is an ongoing puzzle.

Families can wander over Capability Brown-landscaped parkland, take the nature trail, frolic almost freely (£23.20 for a family ticket) in what is probably the most lavish adventure playground of its kind – a galleoned pirate ship with overhead rope walkways, huge slides, swingboats – and admire the house and its eccentric collection of treasures.

But it is a strange exchange, this odd dance of class reversal, in which his lordship becomes the working man and we the leisured class. We come, we pay, we wonder. Why do we drag our children to swanky swings and slides with hundreds of other kids when we could be sitting quietly in our own back gardens? Why does his lordship go on fighting to maintain his family home when he could sell the lot and live a life of luxury and privacy?

Because we enjoy playing our parts. Lord Lansdowne, 66, has expressive hands: the signet ring on the little finger, the detail of his tailoring, cloth covered buttons and turned-back cuffs. As I’m reminding myself that my forebears were probably peasants on his family’s lands (he’s established my ancestry and pointed out his family came to Ireland with the Normans), he’s pausing in his 4x4, to let the hordes pass in their jeans and trainers, and he’s reflecting: “People don’t really care what they look like these days, do they?” But, elegantly tailored or not, he has to graft.

That tension between old and new extends beyond Bowood to the surrounding countryside and on into the Cotswolds. Tetbury, on the Roman road between Bath and Cirencester, and a short drive from the M4, has never been a rave. Its beautiful high street and pillared market house prove there was a briefly bustling period here in the 17th century when the wool trade prospered; the magnificent spire of the gothic revival parish church dominates the landscape and can, apparently, be seen from Prince Charles’s Highgrove home nearby.

We stayed at The Priory Inn, tranquil and decidedly comfortable in this hybrid olde-newe world environment. A family-run, now award-winning, hotel for families like us: transformed from the local lads’ pub by Tanya (who used to run Mark Warner’s family winter holidays) and Dave (a former New York chef) Kelly. Some parts of the building date back to the 16th century when it was a stable block for a nearby priory. Today, it has fashionable clean lines, wooden floors, open fire, leather sofas and coffee-and-cream decor. We had a suite for the children, the two girls in one room and our son in another separated by a shared bathroom; and an adjoining double for us. Huge, comfortable beds; bathrooms packed with local soaps and lotions; baskets of toys for younger children. And, oh delight, a spa where I enjoyed what was described as an essential facial, which turned out to be exactly so.

The food is sourced from local farms, including Prince Charles’s Duchy Home Farm, with a good selection of wines and liqueurs (the wild sloe gin is worth a shot). Favourites among the five of us included the wood-fired pizzas, lamb kidneys with new potatoes and shallots; chicken breast with pan haggerty (potatoes, onions and cheese), broccoli and thyme and mushroom sauce, and a wonderful pistachio rice pudding. For teenies, there’s a children’s menu of home-cooked food without a twizzler in sight.

In the fantasy life we all briefly inhabit when we escape to the British countryside for a few days, we all want to sniff the clean air, rest our eyes on our heritage and pretend we’re at home. As we left Bowood, we’d heard a plaintive cry on the walkie-talkie of an estate worker: “Chavs at gate three.” A reminder that not everyone understands their role in this idyll. Though most of us do. And come back for more.

Bowood House, 01249 812 102, www.bowood-house.co.uk; The Priory Inn, 01666 502 251, www.theprioryinn.co.uk. Summer offer: two midweek rooms for the price of one including beauty treatment for mum, family tickets to Westonbirt Arboretum and dinner for two, £229 per night