Today, 18 May 2014, may well go down in history as the day when Britain finally left India. Narendra Modi's victory in the elections marks the end of a long era in which the structures of power did not differ greatly from those through which Britain ruled the subcontinent. India under the Congress party was in many ways a continuation of the British Raj by other means. The last of midnight's children are now a dwindling handful of almost 70-year-olds, but it is not the passing of the independence generation that makes the difference.

The India those men and women lived in was one that, like its predecessor, was centralised, garrisoned, culturally constricted, and ruled by a relatively small English-speaking elite whose attitude toward the masses was alternately benevolent and exploitative but never inclusive. Universal suffrage gave Indians a vote but not, at least for much of the time, a voice. When that voice was occasionally heard, as it was in 1977 in the elections that followed the disastrously unpopular Emergency declared by prime minister Indira Gandhi, there could be a sudden sense of its almost volcanic capacity to remake the political landscape, but such moments were rare.

Now that voice has been heard again. It has endorsed a new kind of leader in the shape of Mr Modi. He is from the lower castes. He is not a natural English speaker. He has no truck with the secular and socialist traditions that shaped Congress. But, more important, that voice has announced a new kind of India. In the old India the poor were there to be helped, when the elite remembered to do so or when they needed to seek or, in effect, to buy votes. The middling classes were taken for granted and sometimes snubbed. The new India, most observers agree, is not interested in handouts, and refuses to be snubbed.

Instead it wants the obstacles it sees as impeding its aspirations swept away. It has discarded the deference it displayed toward the Gandhi family and toward the Anglicised or, these days, Americanised top levels of society. Whether in its older and purer socialist guise or in its later embrace of the market, Congress has lost its magic, even though the party includes some profoundly decent and well-intentioned people. The core constituency of the Bharatiya Janata party, meanwhile, never shared the non-sectarian values that Congress imperfectly upheld and wants an India where its version of Hinduism has unchallenged primacy.

It should be obvious that these underlying changes in Indian society have brought us Mr Modi and not the other way round. He sensed a great shift in mood and played to it. Nevertheless it matters enormously what kind of man he is. The answer is that we really do not know. It is not only that the question of what role he played in the Gujarat massacres of 2002 remains unresolved. Nor that his personality is rather closed, reserved, even secretive. It is more that the balance in his character between pragmatism and the extremist ideology with which he has been associated since he was a young man is not clear. Pragmatism would lead him to avoid sharp confrontation with Indian Muslims, perhaps offsetting any trouble at home by a peace-seeking diplomacy with Pakistan. It would temper any savage cuts in the subsidy programmes vital to many Indians on the breadline. It would put a measurable distance between the party and the Rashtriya Swayamsevak Sangh movement. And pragmatism would lead to caution in a man who has never held national office before. He has an unexpectedly large mandate, but India is not Gujarat. It is a very big ship to steer, and he will need all the help he can get.

He knows that the aspirations that have swept him to power must be satisfied in part – they could never be satisfied in full – if his new beginning is not to flounder in a morass of disappointment and recrimination from which the temptation might be to take a extreme nationalist way out. Whatever else he is or is not, Mr Modi is a gifted politician. We must hope that he understands that his new India will sooner or later hold him to account.

• This article was amended on 19 May 2014 because an earlier version gave a date of 18 March 2014 when it should have said 18 May 2014.