Sex education is a controversial issue in India, but one man has done more than anyone to promote discussion of the subject. Dr Mahinder Watsa's unusually frank and funny daily newspaper column has become a cult hit. But why does the country that gave the world the Kama Sutra need a straight-talking 90-year-old to teach it about sex?

"Sex is a joyful thing," says Watsa, "but a number of writers tend to become rather medical and serious." Rather than taking the scientific or moral high ground, he prefers to put the reader at ease with a witty one-liner. As a columnist for the past 50 years, Watsa has been privy to the deepest, darkest sexual fears of his countrymen and women. His replies are short, sharp and to the point - occasionally bruising, often hilarious. But whether he chastises or reassures, with every shared reply he educates his readers. "I'm talking their language, they accept it better," he says. "The man talking to you is one of you."

Q: Two days ago, I had unprotected sex with my girlfriend. To prevent pregnancy, we bought an i-Pill. [emergency contraceptive] But in the heat of the moment I popped it instead of her. Can it cause any complications for me?

A: Next time round please use a condom and make sure you don't swallow that too.

Q: I have heard that any kind of acidic substance can prevent pregnancy. Can I pour some drops of lemon or orange juice in my girlfriend's vagina after the intercourse? Will it harm her?

A: Are you a bhel puri [snack] vendor? Where did you get this weird idea from? There are many other safe and easy methods of birth control. You can consider using a condom.

Q: After having sex four times a day, I feel weak the next day. For about five minutes, my vision goes blank and I can't see anything properly. Please help.

A: What do you expect? Shouts of hurray and I am a champion all over town?

He gets about 60 letters and emails a day and responds to them all. "People who got married and are unable to consummate, or women writing they are no longer in love," he says. "I try to help them." Over the years he reckons he has answered more than 35,000 queries - long enough to spot the fake ones. "One knows when someone is trying to pull your leg or whether they are really genuinely in trouble," he says.

Q: What First Aid will we require after having sex for the first time? My fiancée and I have had oral sex many times. How safe is that?

A: You need not join the Red Cross; just visit a sexpert for some pre-marriage counselling. Oral sex is safe and healthy, and she will not conceive through it.

Image copyright Watsa

Watsa was first asked to write a Dear Doctor column back in the 1960s by a woman's magazine. He was in his late 30s and had recently qualified as a doctor. "I didn't have much experience, I must confess," he says.

For the first few months the questions were of a general medical nature - about childhood diseases and so on - but then a different kind of letter began to arrive, from distressed young women in remote areas. They told him that an uncle or an elder had interfered with them when they were teenagers, and now they worried that they would not be married because they'd lost their virginity. "Many even suggested that they'd commit suicide," says Watsa. "This thing about the hymen being intact is very important in this part of the world."

He realised there was a lot of shame and need for advice out there. "These women had no-one to turn to, so they wrote to the magazine," says Watsa. All he could do was tell them not to panic about the wedding night. "I had to advise them to just remain quiet," he says. "Don't worry, your husband won't notice. Nothing will happen." Nowadays Watsa can be more explicit. He explains that the hymen can break in many ways, including physical exercise or some kinds of masturbation - but at the time he couldn't use such plain language.

He realised that many of their problems stemmed from a lack of sex education, and this set him off on a life-long mission to provide it, first through the Family Planning Association of India (FPAI) and later through his own organisation, the Council of Sex Education and Parenthood International, (CSEPI). Throughout it all, he carried on writing.

He still receives letters on the subject of broken hymens today. "That inflames me," he says. "Unfortunately it is still very prevalent." Any men who write in to cast doubt on their partner's virginity get short shrift.

Q: My family is demanding that I get married. How can I ascertain if the girl is a virgin?

A: I suggest you don't get married. Unless you appoint detectives, there is no way to find out. Spare any poor girl of your suspicious mind.

Q: My girlfriend and I are 22 years old. We had sex a few months ago, for the first time, but she did not bleed. How can I identify if she is a virgin? Please help. I am confused.

A: Is this the way you love your girlfriend? You are a suspicious person. Haven't you heard that there are several other ways by which the hymen can split, such as by playing a sport?

Watsa wrote for women's magazines for years until he encountered an editor who censored questions on sexual health. He switched to other publications, including a men's magazine called Fantasy, which featured photographs of naked girls, and later for websites, some aimed at newly-weds.

But most successful by far has been Watsa's latest column - Ask the Sexpert - which he began 10 years ago, at the age of 80, in the Mumbai Mirror. It was the first daily column in an Indian newspaper that addressed readers' sexual anxieties head-on.

Image copyright Atul Loke/Panos Image caption Dr Watsa holds up a copy of his column in the Mumbai Mirror

"Until we ran the column Indian media rarely - if at all - used words like 'penis' and 'vagina'," says Meenal Baghel, the paper's editor. It immediately garnered a lot of attention - not all of it positive. Baghel has had to deal with accusations of obscenity, lawsuits and hate mail, but she feels the benefits of running the column far outweigh any of the troubles the paper has had to go through. "He is undoubtedly the star of the newspaper," she says.

Like most people, she can quote a favourite letter. "Someone once asked him - the gazillionth question on the subject - if their penis will shrink from repeated masturbation. His response: you talk a lot, does your tongue shrink?"

It's a credit to Watsa's wit, inventiveness and endless patience that he finds new ways to reply to the same questions that he has been asked for decades.

Much of his work involves something known as permission-giving - reassuring people that their sexual behaviour is normal and harmless. "The real problem is still masturbation," says Watsa. He gets endless letters from anxious men who worry that masturbation will cause them to lose their strength, their hair, or their ability to have children. The belief that losing semen is detrimental to a man's health is reinforced by traditional belief systems. As a consequence, Watsa has to dismiss a lot of quackery.

Q: I have a small penis and I can't seem to satisfy my girlfriend. My astrologer has advised me to pull it every day for 15 minutes while reciting a shloka [prayer]. I have been doing this for a month but it hasn't helped. What should I do?

A: If he was right, most men would have a penis hitting their knees. God doesn't help gullible, foolish men. Go visit a sexpert instead who can teach you the art of making love.

Q: In the last semester, I failed one subject. My parents got worried and took me to an astrologer… He asked me to remove my pants… He said the ejaculate after masturbation is equal to 100ml of blood, hence my weakness. Is all of this true? Should I stop masturbating and avoid my girlfriend? I am regretting showing him my penis. Please help.

A: The astrologer is a hoax and completely ignorant of sexual matters. Masturbation is completely normal. I suggest you tell your parents you will not visit such frauds again. Not being able to hit bull's eye at academics each time, is normal. Visit your college counsellor.

Q: I'm a 30-year-old man. I have seen a newspaper advertisement that claims some Ayurvedic medicine increases the length and the size of the penis, makes you last longer and can straighten out the penis too. Is this possible? I have had sex 10 times with my girlfriend in the last six months, but I never feel satisfied because I ejaculate too early. Also, how can I increase the size of my penis?

A: The advertisers are just waiting to fleece gullible people like you. None of their claims are true. Learn the art of love-making, which will give you greater joy, than looking for enlargement, which is not possible.

Traditional thinking can cause all sorts of problems, says Watsa, who remembers an army doctor telling him how his soldiers would often return from leave in their native hill country with sexually transmitted infections (STIs) - it turned out they thought living in the plains affected their potency, so before catching the bus home they would have a sexual experience, just to check everything was in working order.

But Watsa has also witnessed massive changes. "India is a very different country now," he says. "Thirty years ago there were very few women writing in. Now it's changed, many women are getting in touch with me." And they don't just have practical questions about how to get pregnant or not - in the past few years they have also started asking about sexual fulfilment and masturbation. He replies with the same humour.

Q: My friend thinks that her breasts are getting larger because of masturbation. Is this possible?

A: No. Does she think her clitoris is an air pump?

Image copyright Getty Images

Despite these signs of women's emancipation, Watsa says he is still occasionally shocked by what his female correspondents endure. "When they write in about the molestation and torture and what their husbands do to them when they are drunk - that worries me," he says.

And not all change is positive. For a start, there's porn. "That's a big problem," says Watsa, who sees how it affects relationships. "The man is looking at porn but he doesn't go to his wife and she gets very upset about it. This is leading to a lot of separations and divorces."

Watsa also laments the loss of joint families, where many generations lived under one roof. "There were always aunts or grandmothers who could explain things to the younger couples," he says. "Now there are more nuclear families and nobody is there to explain how sex works. I hear of a lot of unconsummated marriages. There is no sex education in schools so it's hard for youngsters." Arranged marriages between people who don't know each other is still common, says Watsa. "They expect to consummate a marriage immediately, but in the Kama Sutra there is a section that says it takes four to five days to make friends and understand each other," he says.

Watsa himself did not have an arranged marriage. While he was at medical college in Mumbai he stayed with a big extended family his parents knew - that's where he met his wife, Promila. She was originally from Sindh, he was Punjabi, and they were from different castes. "Normally you would marry in the same caste and class," says Watsa. "However, because we were friends for long, long years we decided to marry."

They had a son and lived in the UK for a couple of years, where Watsa worked as a hospital houseman and registrar. "At the time we had British schooling which followed the traditional English way, so I was quite comfortable," says Watsa. One culture clash came when he recommended yoghurt to a lady with a stomach ulcer but in 1955 there was hardly any to be found. Eventually the matron managed to track some down, imported from Denmark. "It worked," says Watsa. "So I became very popular."

They were happy in the UK but when his father - an army doctor - fell ill, they returned to India, where he worked as a medical officer with Glaxo, as well as running a practice as gynaecologist and obstetrician. "Sometimes I delivered babies all night and then would go to work all day," he says.

A key moment that shaped his thinking was a 1957 meeting of the Congress of Planned Parenthood. He was inspired by a Japanese doctor who explained how he had saved girls from killing themselves after getting pregnant. "The popular suicide spot was around the corner of a hillside on a train track, where the driver couldn't see," says Watsa. The doctor put up posters on the hill saying there was no need to die, he could help. "He did abortions, you see," says Watsa. "He saved a number of people's lives. I was very impressed."

In 1974, when Watsa was working as a consultant to FPA India he persuaded them to introduce a programme of sexual counselling and education. At the time, talking about sex was a great taboo - many felt his suggestion was pornographic, whereas health professionals felt it was "unscientific".

However the FPAI supported him and set up India's first sex education, counselling and therapy centre. "Reactions to this went through the entire spectrum from open hostility, derision, contempt and ridicule, to curiosity, interest, tolerance and reluctant acceptance, and finally to enthusiastic participation," Watsa wrote in 2004.

Image copyright Getty Images Image caption Demonstrating how to put on a condom during an educational event in Bangalore

Although some schools welcomed sex educators in, there were still restrictions. "They would say: 'For God's sake, don't talk about menstruation or we won't allow you into the school'," says Watsa. Ever resourceful, he found a way round it. "What we would do is put a box in the classroom and ask pupils to put in any questions they wanted, and we would answer them." This technique is also used in sex education in the UK, simply to answer the myriad of questions that exist in young people's minds.

Q: Is it safe if penis is kept in the vagina when sleeping?

A: Usually when the penis returns to flaccid state, it will slide out of the vagina. Even if does not, rest assured the vagina will not have it for breakfast.

Taken as a whole, the letters provide a useful insight into the sexual norms and behaviour of a certain urban and relatively well-educated section of Indian society. The gynaecologist and campaigner Dr Suchitra Dalvie has analysed over 500 letters - four months' worth - for an academic study. "The correspondents revealed several things in their letters that they would probably never reveal if asked," says Dalvie. What surprised her most was the gap in their education - many had post-graduate degrees but had no idea about simple things such as masturbation or basic anatomical knowledge. "I think it's an alarming situation," says Dalvie.

Some of the more basic queries included:

•Is it possible to contract Aids from pets?

•What is the difference between anal and oral sex?

•What are periods in girls?

•I am 20 years i want to know what is meant by orgasm

•hello sir i want to ask just one question: does coffee affects sexually??? does it decrease our interest in sex or do breast size decreases???

The letters divided into six broad categories including: basic anatomy and genital concerns (including that old favourite, penis size), sexual intercourse (including anal and oral sex), pregnancy (60% prevention vs 40% conception), masturbation, and erectile dysfunction/ejaculation.

The sixth category, "dilemmas", grouped together a variety of questions about relationships, sex with pets, coercive sex, homosexual encounters, watching porn and fantasizing. "The dilemmas show that we should lay off the morality when educating young people," Dalvie says.

When she presented her findings at a conference on Reproductive and Sexual Health and Rights in Beijing, the audience was fascinated by India's contradictions. They all knew about India as the "mystical land of the Kama Sutra" - the ancient Sanskrit text about the art of love and sensual pleasure - and were astonished to learn about rudimentary level of sex education or even frank discussion about sex in the country. Watsa's Ask the Sexpert column is one of the most candid treatments of the subject for 2,000 years.

Image copyright ALAMY

Attempts to teach children more than the basic biology of reproduction have been consistently thwarted. Hindu conservatives protested against the Adolescence Education Programme (AE) introduced in 2007, with the result that a number of Indian states banned it. In 2013, following the high-profile rape and murder of a student in Delhi, a government committee again recommended that "sexuality education should be imparted to children". But India's new Health Minister, Dr Harsh Vardhan, has a vision for Delhi schools in which he calls for "so-called 'sex education' to be banned". He has since said that he supports it in theory, but without "crudity and graphic representation".

Watsa feels it is unfortunate that politicians are so sensitive about sex education - if anything, he would like to be able to educate children as young as 10, as sexual behaviour is beginning earlier than in the past.

The trouble with sex education

The health minister's comments about sex education have been satirised in a video watched more than a million times on YouTube.

"We really are at the moment going through a sexual revolution, so the current curriculum is wholly inadequate," Ira Trivedi, author of India in Love, told #BBCtrending.

One lesson Watsa says he has learned in the decades he has spent trying to change Indians' attitudes is that "shame [is] stronger than agony" - many issues are still swept under the carpet.

Recently a young professional woman came in to Dalvie's clinic with her parents. She was due to get married, but when introduced to a potential match - a family friend - he had forced himself on her. "They didn't want to report anything to the police," says Dalvie. "Her main concern was: Could I do a hymen repair?" She counselled the young woman, pointing out that the hymen can get damaged in many ways. "It's hard to say all these things to a patient in distress," she says. "I try and build their self-esteem and self-worth. This is not who you are - you are not your hymen."

This kind of informed and compassionate counselling by doctors is exactly what Watsa was hoping for when he organised India's first-ever workshop on Human Sexuality and Family Life in 1976. He put an ad in the paper to attract people from different backgrounds - doctors, social scientists, counsellors, and journalists. Such a holistic, multi-disciplined approach had not been tried before. "We were pioneers in the country," says Watsa.

Image copyright Watsa

One of the journalists present was Ashok Row Kavi, now a gay activist. "I was invited under the cover of being a journalist but I was really supposed to speak on homosexuality," says Kavi. "He gave me free rein - but a lot of people at that meeting were horrified."

The meeting broke all sorts of new ground, says Kavi, discussing for example how male sexual behaviour outside marriage could be a vector for sexually transmitted diseases among women, and how there was no point in treating one partner unless all partners were treated.

The gay activist and the nonagenarian are still close. "He's a very sensible man although he's a bit of a prude," Kavi says about the man he calls his surrogate father. "He's a little sceptical of questions about homosexuality but his answers are straightforward." He quotes a letter from a man who had a very happy marriage but had fallen for his male boss. "The answer was: 'For heaven's sake, why sacrifice such a wonderful marriage for your boss, which may cause problems at work?'"

Kavi's favourite Watsa letter is about a man's intimate affection for his pet goat.

Q: I am a 32-yr-old happily married man from Karjat. Recently, I've been having mixed feelings about cheating on my wife. I have a goat; her name is Ramila. Over the past two months, I have been thinking about how it would feel to make love to her. Is this normal? Will I contract a goat-related STD? Please help!

A: Ask Ramila whether she would like it! Bestiality is not considered normal and it is illegal.

Image copyright Getty Images

Not many in India would consider Watsa a prude, to use Kavi's word, although in his personal life he seems to have been quite traditional. His wife, Promila, was a housewife and brought up their son while he worked hard. He gave up his obstetrics practice in the early 1980s to dedicate himself to counselling and education.

Promila died in 2006 and he has outlived his younger siblings. One of his granddaughters, a dentist, recently moved in with him in Mumbai.

He seems to have no intention of retiring - as well as answering letters, he still runs a sexology clinic from his apartment overlooking the Arabian Sea. Sometimes he sees older couples, in their 60s or 70s - still youthful from his own perspective - who want to improve their sex life.

He is writing a book, too - not an autobiography though, which is a shame when you consider how long and varied his life has been. Watsa has an extraordinary memory from when he was about seven years old, and the family lived in Rangoon - Burma then was still part of the British Raj. "We visited a very rich family and during the meal I felt some tickling under the table," says Watsa. "It was a servant girl with long hair, brushing our feet so the mosquitoes wouldn't bite." He is a survivor from a different era.

"You forget his age because he is so forward thinking," says Dalvie. "He is always five steps ahead on social issues - he doesn't moralise, he is just always ready to move on."

Watsa recently received a prestigious award for his services to sex education - at the ceremony, Kavi presented him with a bunch of condom-covered bananas, delighted at the gasp of horror it elicited from the audience. Watsa got the joke though - bananas are often used to demonstrate how condoms work.

The crowning glory of a long career, however, may well be his Ask The Sexpert column.

"I know many of us in the profession, the first thing we do when we get the paper every day is to turn to his column," says Dalvie. "It can seem flippant but it's part of his charm and wry sense of humour - a way of telling people not to take their problems so seriously."

Watsa receives the odd letter of thanks from people who benefited from his advice. And when he attended a wedding recently a woman pointed him out to her son, saying: You are here thanks to that man. Watsa blushed - but in this case it was in the delivery room that his help had been so vital.

"I'm still standing on my feet," says Watsa. "Perhaps I can carry on for a bit longer."

Dr Watsa spoke to Outlook on the BBC World Service. Listen again on iPlayer or get the Outlook podcast.

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