One of the author's favourite recent photographs shows her perched on the bonnet of her car, about to embark on a solo, two-week road trip from Sussex to the wilds of Scotland, taking in Eryri (Snowdonia), Lancashire, the Lake District and Yorkshire. She had no idea this research trip - for her book tracing the story of British holidays over 400 years - would reveal her homeland as somewhere she barely knew. As a southerner, it was the northern half of Britain she needed to discover, stitching together a route of museums, archives and classic seaside resorts that once blazed so brightly. Cumbria she'd visited before, but the Conwy coast, Lancashire countryside, Blackpool, Morecambe, Scarborough? All unknowns.

First stop: Eryri, where her hotel, the Royal Oak in Betws-y-Coed, had been welcoming artists like JMW Turner since the late 18th century. Fifty years later it became the hub of the country's first artists' colony, drawn by the dramatic beauty of the Gwydir Forest and Glyderau peaks. Over coffee, hotel manager Katie Valentine explained that the artists called the area home - David Cox, Henry Clarence Whaite, Thomas Collier among others - until Betws railway station opened in 1868. "At that point," she said, "many moved to houses further up the valley, grumbling that the place was becoming flooded with tourists." It seems overtourism, the author notes, is far from a contemporary trend.

From Eryri, a short hop to Llandudno, a beach town so pristine it felt like a Victorian theme park resort. "In some ways it is," Judith Phillips, trustee of the Llandudno Museum, told her. "The family who built Llandudno in the mid-19th century - the Mostyns - still own much of it now, and control everything from what colours people can paint their hotels to what businesses are allowed on the promenade." The museum made plain that much of British history isn't in great city museums but in libraries, archives and small museums on quiet high streets, often run by passionate volunteers with encyclopaedic knowledge.

Driving from Llandudno up to Lancashire along the North Wales Expressway, she whipped in and out of tunnels, emerging to see great swathes of cobalt-blue Irish Sea stretching to the horizon. Further into the journey, she was pointed towards early editions of the very first guidebooks to the Lake District, written by Thomas West and William Wordsworth, at the Armitt Library in Ambleside; shown handwritten letters by Queen Victoria at Blair Castle (including her personal recipe for potato salad); and told wonderful stories of Wakes Week holidays in Blackpool by the dapper Richard Croisdale at Blackburn Museum - their longest-serving volunteer, at a sprightly 90 years old.

Blackburn's grandiose Victorian museum and Bolton's neoclassical town hall stand as legacies of the era when Lancashire towns were affluent manufacturing bases home to tens of thousands of factory workers. The Georgian streets of Richmond are like a mini Bath, but steeped in Yorkshire heritage. But perhaps nowhere confounded expectations more than Blackpool. Arriving on a Friday night, the promenade buzzed with lights and life; the illuminations blazing all the way to the tower, kids skipping along the seafront entirely unaware they had been brought to one of the most deprived towns in the country. "We are a town of extremes," said Claire Smith, co-owner of Number One South Beach B&B. "We have pockets of absolute joy next to complete caverns of woe. There's no blending. It's either amazing or awful."

Claire and husband Mark shared stories of Blackpool in the 1970s, not least his coming back from the pub as a teenager to find his parents had let his bedroom - along with their own - to guests, leaving them to sleep in the lounge. This was the era when guests queued in dressing gowns to use bathrooms, landladies locked doors between mealtimes, and peach Melba was the height of culinary flair. "They were simpler times, people expected much less," Claire told her, a little wistfully. "But I do think people were happier." Still, plenty of joy remains: visiting the Pleasure Beach as it opens on a Sunday morning, families stream in, the first coasters rattle skywards, a general air of giddy excitement starkly counterpointing the rundown streets elsewhere.

So many preconceptions were corrected or reversed: the elegant St George's Hotel in Llandudno showed her not all grand dame seaside hotels are faded or old-fashioned. And while Britons love to run down their own seaside resorts, she saw beaches to rival anything the Med offers, from Scarborough's South Bay to Morecambe's vast, empty sandscapes. Beyond the seaside, it was Scotland that really blew her mind. Following in the footsteps of William and Dorothy Wordsworth, who toured the Highlands and Lowlands for six weeks in 1803, she headed up the western flank of Loch Lomond, entirely unprepared. Dusk fell as she drove across Rannoch Moor - a silent, pockmarked moonscape seemingly bereft of life, save for a lone pair of car headlights somewhere up ahead. Then, in the distance, great hulking mountains rose up, guarding the entrance to Glen Coe. It's a landscape so forbidding that when she pulled up at the Three Sisters viewpoint, she was genuinely relieved to see another couple, so she didn't have to stand alone among the ominous peaks.

Scotland had stories, too: from the spruce and redwood trees planted in Glen Coe by Lord Strathcona in the 1890s to make his Canadian wife feel at home, to Queen Victoria taking the first ever fly-and-flop (train-and-flop, perhaps more accurately) at Blair Castle in 1844. Her visit was hosted by the 6th Duke of Atholl, who promised the security of his own private army (and had to move out of his own castle during the royal stay). It was the beginning of a royal love affair with Scotland that led to the purchase of Balmoral in 1852.

When she got home - 13 days and 1,600 miles later - her husband took the same photograph of her perched on the car. It had been more of an adventure than she could have ever imagined: to lands unknown on the island she calls home.