“Don't talk about Castro,” said our driver to our guide on the way from the airport. He needn’t have worried. No Cuban will discuss Castro with foreigners. His health, even his whereabouts, are state secrets. With only state TV channels and the official newspaper, Cubans know less than we do. Whether you go on a package tour or hire a car and stay in the private houses licensed to host tourists, you’ll have to use your eyes and work it out for yourself and no two people will agree. Sitting in the sun, drinking cocktails and arguing about it is one of the joys of a Cuban holiday.

Thirty years ago, as a middle-ranking MI5 officer, one of my responsibilities was to keep an eye on Cuban intelligence officers in London. In those Cold War days we thought them a threat and I couldn’t have travelled to Cuba. Now it’s difficult to imagine a threat, even though the revolution still loudly asserts itself. Motorway hoardings and state-sponsored graffiti in the villages announce “Revolution is Eternal Victory”, or, more sinisterly, “No-one Will Quit”.

It isn’t easy for Cubans to quit. The revolution seems to be propped up by every kind of restriction, yet at the same time, it still proclaims its youthful ardour. At Che Guevara’s memorial at Santa Clara, a place that feels like a shrine, photographs of the young revolutionaries line the walls. Che and Fidel slouch in chairs, looking in their fatigues eerily like Battle of Britain pilots with beards and cigars. You cannot but reflect that revolution is the fun part; what counts is what you do afterwards when difficult decisions have to be made.

Cuba is increasingly a magnet for foreign tourists seeking sunshine or a holiday with a difference. They are welcomed because they bring the hard currency essential since the Soviet prop disappeared. Last year, 2 million came, mainly from Canada and Europe; none, of course, from the US. The old mutual resentments live on. On every bookstall you’ll find English books with titles such as CIA Targets Fidel and a George Bush with vampire’s teeth stares out from posters. Whether all this will continue when Castro dies, who can say?

But tourists are also a threat, and to prevent them getting under its skin, Cuba mounts a theatrical performance. Here is a sunny idyll where everyone smiles and greets you with a cheery “ Hola”. Whenever you sit down a band appears to sing and dance. There is rural beauty and neo-colonial charm. Cubans are decently dressed, the children well cared for, and nobody looks hungry. Education and healthcare are excellent, public order seems good.

But when you look behind the scenes, all visible infrastructure seems to be falling to bits. Outside the towns there is little public transport and even bicycles are rare. On the motorways, people congregate under every bridge and tree, organised by men in yellow, who ensure that government vehicles stop to give lifts. In rural areas travel is by Soviet-era lorry, bus, rickshaw or on horseback. Tourists attract street vendors and beggars wanting anything Western – chewing gum, pens, and, of course, the convertible peso, the tourist money. Beneath the smiles and the genuine kindness of Cubans, there is a palpable sadness and a sense of an extreme hardness of life.

Visitors throng the Jagua Hotel in Cienfuegos, enjoying the swimming pool and the buffet. In the beautiful Viñales Valley, to the west of Havana, you can sit on your balcony at the pink Los Jazmines hotel and watch, far below, a peasant working the tobacco fields with a wooden plough, his voice encouraging his oxen. A glorious sight, until you reflect that under the curious double-currency system in which the convertible peso is worth 24 times the local peso, it will take him months to earn the single convertible peso you’ll give your chambermaid.

Even for the tourist, arrangements mysteriously break down. You wanted to stay at Los Jazmines? Beware of being relocated, as I was one night, to La Ermita, farther up the valley, where water cascaded through the ceiling, and I dossed down in jeans and two jerseys to survive the draughts from the broken windows.

In Havana, many of the old colonial buildings are falling down, their pillars and balconies propped up with wood. But if you look through the windows, the insides are often lovingly cared for, clean and polished, rugs on the tiled floors and lace antimac-cassars on the chairbacks. A tourist can drink at the Floridita bar, largely unaltered since Hemingway’s day, where the barman and the daiquiris are perfect, or lounge in the sun on a huge basket chair at the Hotel Nacional, a 1930s masterpiece.

You’ll meet the ghost of Graham Greene everywhere: in the Sevilla Hotel, where Hawthorne of MI6 recruited Mr Wormold the vacuum-cleaner salesman as Our Man in Havana, the bar is no longer dark and sinister, but decked out with pretty Moorish tiles. There’s no sign of a vacuum-cleaner shop in Lamparilla Street, and the Wonder Bar, with its shades of the murdered Dr Hasselbacher, is, alas, no more. But across the road, on the corner of Virtudes, the colonnade where the beggar limped by still stands, just as Greene described it in 1958.

You can visit a cigar factory where the tobacco is rolled by hand, hire an old Cadillac or, in the car museum, admire a 1926 Willys Whippet that could have belonged to Bertie Wooster. But if you are a local you must travel in the camelos – long buses, overcrowded and filthy.

Cuba presents different faces to different people. Some will see a socialist state working as it should, providing equality, healthcare and education for all. To others it is a police state going nowhere, with crumbling buildings, medieval agriculture and inefficient services. To many it’s just an inexpensive and sunny place to swim, drink rum and enjoy music. If you want a different kind of holiday, go there and see what you think.

Need to know

Travel Editions (020-7251 0045, www.traveleditions.co.uk) offers 11-night escorted tours of Cuba, including three nights in Havana, three in Viñales and three in Cienfuegos, departing from November to May, from £1,119pp. Just You (0800 9158000, www.justyou.co.uk) has 14-night escorted tours covering the length of Cuba, including Havana and time on the beach, departing from November to May, from £1,699pp with no single supplement.

Times recommends

• 'New York has lost its edge'
• The UK and Ireland's 25 best Christmas events
• Chalet Chef 2010: the winners