He has become such a public figure that invariably, if we are out, someone will want to speak to him, have a photo taken with him or just greet him with kind words. Beyond that, Ratan remains the same as he has always been — he loves the simple things, a good laugh, long conversations, if not lolling in his room, then on the phone, playing with his dogs, flying, tinkering with his cars and, when the mood strikes, he is a great shopper.

What has also not changed is that he makes no distinctions in the way he treats people; everyone in his book is a very important person, whoever she or he may be; everyone gets that same easy conversation, a pat on the back and a word of encouragement.

What also has not changed, as many who work with him will probably recognise, is his way of conveying his frustration when things go awry — never a shout or harsh words, but rather a quiet word, pursed lips and a deadly look (we call it the “Ma look” that we think he inherited from our mother).

Also unchanged is his sensitive nature and his hurt when he has felt let down by those he trusts, disappointed by the turn of events, or hurt by accusations and backbiting.

We are also asked when he developed his love of planes and cars. According to our mother, long before we were born, and when he was a very young child. And here is proof, a painting of him, done when he was five or six, together with his favourite things!

We have also been asked what Ratan would have done if business and the Tata group had not come to dominate his life. That is easy. Ratan would have been an architect.

The first structure he designed in India was his mother’s home — with much goading from her. The house is a delight, and Ratan spent many hours overseeing its progress, giving it his usual sense of detail and aesthetics. There were many clashes between his preference for the modern and straight lines, and our mother’s preference for a mix of the modern and the traditional, but the product is a beautiful and comfortable home.

Ratan Tata with his sisters, Deanna Jejeebhoy and Shireen Jejeebhoy

We are a close family and Ratan has a deep commitment to family. Much has been said about Ratan preparing Tata Industries’ first strategic plan while at the bedside of his dying mother. Few know the depth of his relationship with her; we always made fun of him as our mother’s favourite child, but he was indeed a wonderful son. She was a strong and upbeat woman, but a day before she went in for her life-threatening surgery, she broke down.

An abiding memory is of Ratan talking her through her fears, reassuring her, and helping her regain her flagging optimism. They shared a close relationship, he sought her advice, he supported her in hard times, they were friends as well as family.

We have always been close, both in anguished and in good times, there are lots of laughs and teasing — Ratan is known teasingly by his sisters by many names, ranging from “patriarch of the family” to “chota baba”. And there is confidence that we are there for each other — whether it is commiserating over a failed romance, supporting each other in grief and bad times, discussing careers, criticising each other, or discussing dreams for the country, Ratan is fully engaged.

Upholding values is important to Ratan. Many will remember Ratan for sticking his neck out, for speaking his mind, whether it was his plea to all of us to stand up and be counted at the time of the Mumbai riots in 1993; many will remember his 'Bombay is not for Burning' plea on the front page of many newspapers (an ad he paid for himself), his appearances before the Srikrishna Commission, or his more recent tweet in support of the prime minister who “has led our country with great personal dignity and integrity”, yet acknowledging that our country has lost its growth momentum, and calling for bold action, “removing the road-blocks to growth and controlling crony capitalism”. He takes great pride in doing the right thing, and this extends into his personal life.

Some years ago, Ratan had a surgery abroad that zapped him of his strength, and when it was time to return to India, the prospect of a long flight with stopovers midway was quite daunting. A close American business colleague kindly offered him a company jet that would bring him back to India far more comfortably and, as his sisters, we inwardly jumped at the idea of a less stressful trip home for him.

Ratan was touched by his friend’s thoughtfulness, but politely refused; he said it was not ethical. He often says that sticking to his values is the only way he can sleep at night, and his life is replete with instances, small and big, where he has stuck to what he believes is right and just.

And probably well hidden from public view, Ratan has another side to him — an irreverent prankster, and a great mimic and tease.

Far from being the shy and silent person he is often portrayed to be, Ratan has a great ability to laugh and make others laugh, often at his own expense. He can mimic anyone, with accent, intonations and actions perfectly captured.

He is a great tease, and when we are together, not an occasion goes by without his taking the opportunity to tease. His sisters are a great butt of his good-natured teasing; many who have heard our interactions have laughed at the banter that goes on between brother and sister, and some have commented on how fortunate we are to have such a relationship. We are indeed.