Caravans - you either love 'em or hate 'em. Aficionados see them as the acme of the holiday experience, combining the fresh air and informality of camping with a few home comforts such as warmth, cooking facilities and your own toilet. Their eyes are likely to mist over as they talk of life on the open road, a carefree, freewheeling way of seeing the world without having to pay the earth when you get there.
Then there's everyone else - the people who seem to spend half their life stuck in a long queue of cars behind some lane-clogging monster, crawling along like a giant snail on wheels. To them, caravans are a very English type of joke, suburbia on the move, towed by earnest scoutmaster types who force their families to spend two weeks in a muddy field listening to the rain drumming on the roof, while endlessly deriding the needless expense of the kind of holiday their children's friends will be boasting about at school after the summer break.
The caravan shown here was photographed during the Second World War, when rationing and restrictions on travel made a weekend in your own mobile country residence a luxury.
This is an "aero"-style caravan, so called because of its streamlined shape, which from the 1930s began to replace the box-like design that had prevailed since caravans were drawn by living, single-horsepower vehicles.
The first car-pulled caravan rolled on to the road in 1914 and, in the years after the First World War, the caravan was presented as a way of leaving the smoky cities for the simple joys of the countryside. This was getting back to nature, echoing the free an easy life of the Gypsy, and promoted by such outdoor spirits as the founder of the scouting movement, Robert Baden-Powell, a longstanding president of the Camping and Caravanning Club.
As caravanning grew in popularity, purpose-built parks sprang up, along the coast or in places of natural beauty, often run by local clubs and groups of enthusiasts. As well as organising get-togethers in caravan parks, clubs began a tradition of staging rallies at events such as country shows, showing increasingly sophisticated vehicles, which today can cost up to pound;20,000.
Despite the shift in holiday habits towards cheap weeks on the sun-soaked beaches of southern Europe, caravanning has proved a durable pursuit. There are about one million caravans in Britain. The bulk of these are touring vehicles towed by cars, but almost 100,000 caravans are used as permanent homes. The Caravan Club claims 800,000 members, and the industry has an annual turnover of around pound;2.5 billion and employs more than 90,000 people.
But caravanners, with their reputation for self-sufficiency, are not big spenders. A recent Scottish survey revealed that the average daily expenditure of the caravan holidaymaker is pound;33.59 - more than enough for a copy of Practical Caravan for those rainy days inside.
Camping and Caravanning Club: www.campingandcaravanning club.co.ukNational Caravan Council: www.nationalcaravan.co.uk This photograph is from A Century in Photographs: Travel 1900-2000 (Times Books, pound;16.99), which captures developments in transport and their social impact with a picture and related story for each year of the century