Having a gold-buttoned butler turn down the sheets of your bed on a train travelling through the African plains of the Karoo is spoiling and surreal. As is soaking in a gloriously deep, warm bath with a glass of champagne in hand, bubbles reflecting the gleam of marble and gold bathroom fittings, as the train thunders through the South African vastness.

The Blue Train thrusts its way past savannah and mountains, waterfalls and dustbowls on its 1,000-mile, 27-hour journey from Pretoria to Cape Town (there is also a service to Durban). Eagles blithely hover over it. An ostrich stares before running off, feathers astir, feet like clockwork. Nature’s sideshow unfolds in the heat and dust as you settle in your fast-moving air-conditioned luxury cocoon.

The trip is for many the ultimate holiday: honeymoons, anniversaries and big birthdays are often the bonding link to those who have taken this dramatic journey since the service’s inauguration in 1946. Or sometimes it’s just a sense of adventure and romance. This is Agatha Christie fantasy time – the delightful time warp of an immaculately reproduced train interior from a bygone era, all gleaming mahogany and cherry wood, creates inevitable comparisons to the Orient Express.

Time seems to stand still while the locomotive powers forward through exotic territories. Intrigue beckons: for instance, who is the gorgeous divorcee in the cabin three doors down, who appears to change her outfit for every meal? What are the chic couple, all in white, talking about so animatedly? The only part of the fantasy that’s missing is Hercule Poirot himself.

We boarded in Pretoria at 8am and were happily seated as the loco pulled out of the station at 8.50, hauling its 18 smartly painted blue coaches with suites for 74 guests, plus dining and lounge areas. We had already been shown our own accommodation by our butler, a gracious and highly efficient lady called Eunice Radali – and our first reaction had been to wonder where on earth the beds were.

Eventually, Eunice would solve the mystery, but in the meantime we’d got acquainted. “My mother is my role model,” she told me and my daughter, who was my travelling companion. “Her strength inspires me tremendously.”

I rather hoped my daughter would reply in the same vein, but unfortunately she seemed to be too busy scouring the suite for clues as to where we could possibly sleep.

Later on, as night fell, Eunice conjured up beds up from what had been two comfortable armchairs with matching footstools (we had a twin-bed suite; doubles are also available). Set within satinwood-panelled walls, the inviting beds had crisp white cotton sheets and goose-down duvets. And you’d have to look at the en-suite bathroom for a long time before you were reminded of British Rail: we had a marble basin, gold fittings and a choice of bath or shower. Travel light is the way to go, as Blue Train monogrammed dressing gowns are ready and waiting.

There’s even room in the suites to fit a writing desk by the window, for postcards home. Mobile phones work fine, though there is no WiFi, but who minds swapping their laptop for good old-fashioned pen and paper when all letters are stamped by the Blue Train’s exclusive on-board postal service?

It’s not all retro, though. There is a movie channel – for when the view becomes the deep, black, bush night – and a driver’s eye camera allows you literally to track the tracks. The suspension, braking, lighting and underfloor heating systems have been designed for maximum comfort in motion, and there are two technicians aboard in case of any hitches.

We’d already had breakfast in the Blue Train’s private reception building in Pretoria: croissants, smoked salmon and eggs benedict proffered on a silver tray, with champagne and fresh orange juice. Before lunch, Eunice returns to offer us a cocktail before we head to the dining car.

As we feast on ostrich fillet and Cape wine, we forge a path through the country’s history. We roll across the gold fields of the Witwatersrand and make a stop for another precious commodity. Diamonds were discovered in South Africa in 1866 and fabulous fortunes were made at the country’s biggest diamond mine, Kimberley, from 1871. The “Big Hole” is the largest excavation dug with picks and shovels in the world. Mined to a depth of about 790ft, it has a surface area of 42 acres. By August 14, 1914, 22.5m tons of rock had been excavated, yielding about 2.7 tons of diamonds.

At the mine’s museum you can sift through diamond-bearing gravel looking for your own best friend, and experience a diamond mining operation, complete with blastings. Don’t expect any bargains, though: diamond prices, set by De Beers, remain pretty standard throughout South Africa.

On the northbound Cape Town-Pretoria trip, the train stops at Matjiesfontein, a Victorian health spa founded in 1884 in the Little Karoo. It was restored in 1970 and declared a national heritage site in 1979. Visitors can tour its immaculate streets in a red open-top bus.

All very fascinating, but in the heat of the afternoon, the lure of the clubby, air-conditioned train is as welcome as the cool of the hill stations once were to the memsahibs of imperial India.

Sustained by nothing since lunchtime but high tea (sandwiches, scones and cake) and a glass of sherry at the Kimberley pit stop, it’s all the luxuriating traveller can do to summon the butler to press our clothes for dinner – lunch is informal, but evening dress code is jacket and tie for men and “elegant” for women – and make our way to the dining car for Knysna oysters, Karoo lamb and more well-chosen South African wine.

By now it is dark, dark, dark outside: apparently, the semi-desert lunar landscape of the Karoo doesn’t offer the passenger any great variety or excitement, so we needn’t fret about missing out on the view. In fact, for anyone from overcrowded Britain, the prospect of a night unlit for vast swathes by anything but the stars is as exotic as any sight under the sun.

In the morning, we awaken to a different outlook: the well-tended vineyards of the Cape and, looming ahead, Table Mountain. There’s time for a leisurely breakfast in bed, brought by the attentive Eunice, and then we’re at our journey’s end, Cape Town station – but ready for our next adventure.

An hour or so from Cape Town is the buzzy coastal town of Hermanus: whale central from May to December. That’s when you can see the whooping, wallowing, wonderful southern right whales offshore, during their annual visit north from sub-Antarctic waters. They mate, calve and rear their young here, then migrate in summer, when krill are plentiful at more southern latitudes.

Birkenhead House is the place to stay, a white-fronted villa by the sea where foie gras and partridge are as likely to be on the menu as passion fruit and oysters. Modern, chic and ever smiling, this is the seaside hotel that Britain dreams of but can never create. As well as the main hotel’s 11 rooms, there is a new five-room villa with enough high-tech gadgetry to keep any teenager goggle-eyed if the adults want a quiet martini to themselves as the sun sets.

Back to those whales: the sheer drama of being by the sea with these vast cavorting mammals just yards in front of the glass-fronted dining room, amid glorious sunshine, is spellbinding and unforgettable.

— Kathryn Greig travelled with Africa Travel (0845 450 5705, www.africatravel.co.uk). A trip including the Blue Train, one night at the Saxon hotel in Johannesburg, three nights at the Cape Grace hotel in Cape Town and three nights at Birkenhead House, Budget car hire and return flights with British Airways costs from £2,665 per adult and £1,250 per child under 12