Little will have changed since the school days of famous old boys like Winston Churchill, the Duke of Westminster and Pandit Nehru, the first prime minister of India, all raised on classics, rugby and cricket.
But rather than beginning their school careers strolling across 360 acres of chilly north London parkland, these latest recruits will embark on their education in the wet heat of a Thai spring.
Around 130 pupils are expected at the first classes of the new Harrow International School in Bangkok, to receive intensive tuition in English ready for the beginning of the school year proper in September.
Eventually the school hopes to attract 1,800 youngsters from across the Far East, who will doff their boaters to the beaks at a purpose-built site outside the Thai capital, designed to be a little oasis of old England.
Michael Liddiard worked at Harrow for 18 years before moving to found the international school. "The aim," he says, "will be to take a child at any time during his or her schooling and swap them with a child at Harrow without them being able to tell the difference."
The school will have an English head and staff, and will teach the full range of GCSEs and 25 A-levels currently enjoyed by Harrovians at home. Pupils will not be spared the compulsory Latin, but there will be additions. Girls will be welcome (the original Harrow is all-male) and the new school will also break with the original's tradition of boarding by offering places to day pupils.
The new school is just part of the multi-million pound industry which has grown up to capitalise on the academic reputation and social standing of Britain's public schools and universities. Until recently, that meant thousands of school and university students would come to Britain for their education, but Harrow's Far Eastern branch is part of a trend towards exporting our expertise to other countries.
The new Harrow school aims to draw in children from across the Far East - the sons and daughters of expat diplomats and businessmen, as well as locals. The proportion of Thai youngsters will be kept to 30 per cent, partly to satisfy local legislation and partly to ensure that English is used outside lessons as well as in class.
"The ethos, discipline and the Harrow education will be the same," Mr Liddiard said. "In the senior school the children will wear boaters and the uniform will be like the summer dress at Harrow.
"We are going to play cricket and rugby We will have an all-purpose sports ground with football and rugby pitches.
"People are looking for an old-fashioned schooling which provides their children with the impetus both to learn and to take part in learning. Local schools have 50 or 60 to a class and teaching is by rote. We will be providing classes with a maximum of 25 and children will be encouraged to take a full part in their education."
Fees will run to pounds 3,750 a year, about one third of the cost of a place at Harrow in England. Staff say the collapse of Asian currencies may have helped the school's prospects, by inflating the cost of sending children to England.
As many as 20,000 foreign children board at private schools in Britain, and demand is growing. One in five comes from Hong Kong and the Far East, but substantial numbers hail from mainland Europe and North America. ISIS, the Independent Schools Information Service, estimates that three-quarters of the foreign children at independent schools end up at UK universities.
It's a valuable trade: universities say that the 154,000 full time foreign students - 17 per cent of the total - bring in pounds 575m a year in fees, and spend pounds 756m a year while they are here.
Head teachers put their schools' popularity down to educational standards, and the desire to learn the international language of business. Privately they admit that public schools have become chic among the moneyed international classes.
Harrow is joining a minor invasion of the Far East by the public school fraternity. Dulwich College, which schooled PG Wodehouse and Raymond Chandler, opened a school on the Thai island of Phuket last year. The buildings, a Thai interpretation of Dulwich's Victorian premises in South London, are designed to evoke the English public school atmosphere.
Graham Able, master of the original Dulwich, said: "There is a perceived quality in English education, both at secondary and tertiary level, and certainly some people would rather go English than American."
Dulwich, founded in 1619, has employed business tactics pioneered in the world of the burger bar and set up the International College as a franchise, using the London school's curriculum and name.
Franchising has become something of a dirty word in education after a series of high-profile scandals involving university courses licensed overseas. Mr Able admits that such ventures are a risk for an ancient institution, and has taken responsibility for checking his colleagues in Asia once a year during a personal visit to the new school.
At Pocklington School in Yorkshire, staff have opened up a foundation course for foreign students in collaboration with Hull University. Given the praise heaped on education abroad, it is perhaps surprising that the greatest growth is in students from France and Germany. Head teacher David Grey believes he that it is the breadth of our education which has great appeal. "It prepares children to be independent and go out into the world with a head on their shoulders. But I do think there's a certain social cachet about it."
The spirit of the stiff upper lip will certainly live on at the new air-conditioned Harrow, which will transplant the team sports of rugby and Harrow Football, an ancient game said to be suited to the Middlesex clay, to the heat. Michael Liddiard said: "It does get fairly hot here, but during the rainy season it's almost as muddy as it is in England."