Fifteen years ago an estimated 2billion people around the world saw the funeral service of Diana, Princess of Wales after it was broadcast from Westminster Abbey. How is she remembered and what effect did she really have on the lives of those who observed her life and watched the dramatic and poignant events of that day?

Quite often lately I've heard the view that Diana's influence can be seen in the way the remaining members of the royal family now conduct themselves and that this was most obvious during the recent Diamond Jubilee celebrations, London 2012 and the current Paralympics. It seems they are exhibiting a new level of informality and are more approachable - more user-friendly. Certainly the senior members are enjoying a level of acclaim and general affection from the public that they did not achieve when Diana was alive.

What I struggle to recognise in any of them, young or old, is the tactile, emotional content of Diana's interactions with people, especially the sick and damaged wherever she met them. I'm being unfair of course. The highly developed empathetic ability she allowed herself to share was not common, nor is it shared by any member of the current royal family as far as I can see. Still it seems to me that if there is a new-look monarchy it is only marginally different from the old.

I can't help being reminded of the animosity that existed towards Diana from the organisation around the royal 'firm' - the 'men in grey' as Diana called them. It's certainly true that she challenged the Queen's authority and Establishment norms with her controversial campaigns and refusal to be compliant. Championing better treatment for sufferers of HIV AIDS and a ban on anti-personnel landmines were neither politically correct nor tasteful to many who would have had her toe the line and do as she was expected.

The idea that she might not be prepared to sacrifice her health and wellbeing on the altar of unhappy duty, pomp and ceremony surely rankles still. Perhaps there is some substance to the growing opinion that the People's Princess, the rebellious Spencer, is being airbrushed out of the Windsor history.

And what of the British press - can we find Diana's legacy in any changes there? Has it altered its behaviour after its insatiable appetite for stories and pictures of Diana contributed to her final moments in the tunnel under Pont de l'Alma in Paris that August night? It seems not if recent arrests associated with phone hacking, reactions to Harry's holiday snaps and the Levinson enquiry are anything to go by.

Today the media deification of Kate, Duchess of Cambridge has to be a worry. How long before that same appetite for stories and photos becomes so voracious that it begins to affect her health and happiness, as it did Diana's from the moment she was linked with Prince Charles? Can we trust the press to take a balanced and less cynical view than in the past after their experience with Diana?

Not so long ago a poll in the UK saw Diana voted third in the popular list of 100 Greatest Britons, behind Winston Churchill and Isambard Kingdom Brunel. Unlike the two above her in the list Diana cannot have been admired for heroic acts in war or commerce. Her stubborn resistance was not against an invading army nor did she seek to tame nature and overcome it with amazing feats of engineering. The admiration Diana received was for her heroic resistance to the idea she was not entitled to the same opportunity as anyone else, the opportunity to follow her own path, and for her efforts to come to terms with her own frailties.

If Churchill and Brunel inspired people to see hope where they believed there was none, or opportunity where they thought it did not exist, then Diana has earned her place for the same and for enabling us to recognise we can change who we are and overcome almost insurmountable challenges in the pursuit of our dreams.

I believe a major part of Diana's legacy is in the subtle but emphatic effect she had on the minds of so many of the people who observed her life and saw her funeral. It is in the shift of perception she brought about in the psyches of ordinary people all over the world when she challenged us, with her work with AIDS patients, leprosy sufferers and the severely disabled, to find new levels of compassion, caring and tolerance within ourselves.

Today we see that legacy in the biggest Paralympic Games ever held. Who can doubt that the awe we feel when we see elite disabled athletes striving to excel in sport, will not be reflected in our attitudes towards the similarly disabled we meet now in every-day life, as we recognise they too are striving to excel? For me, Diana's real legacy then is that she demonstrated how to love. What do you think?

Follow Stephen M. Twigg on Twitter: www.twitter.com/mydianastory