Field Marshall Mannerheim of Finland is one of the giant, if relatively under fêted, figures of European history. Called out of retirement at the age of 72 to lead tiny Finland against the might of the Soviet Union in the Second World War, his achievements were not only to win two wars, but also to know when and how to sue for peace. It is this latter aspect which is almost certainly the most significant reflection of the wisdom of ageing and experience.

In his achievements of later life he mirrors the careers of a number of major political figures whose supreme contributions arose at a time when most citizens are enjoying retirement, including Winston Churchill, Charles de Gaulle, Ronald Reagan, and Golda Meir. These narratives are helpful metaphors for illuminating the relatively neglected concept of the demographic dividend—that which we all have gained from the dramatic increase in longevity.

So when giving talks to the general public, students, or trainees, in addition to drawing on the creativity of later life—from the art of Matisse and Monet, through the sculpture of Bourgeois and Calder, to the movies of Kurosawa and Eastwood—I also discuss the gains we have been gifted in our political system, but also some other important lessons in terms of gerontology.

These include the fact that late life can be the time when we find salvation from earlier missteps and error, and provide encouragement that it is never too late to achieve—think of Gallipoli for Churchill, or the relative obscurity of de Gaulle’s career in the immediate post war years.

In addition, we are also assisted in escaping from the sometimes over sentimental portrayal of the “golden years” by the very clear flaws in the make-up and some aspects of the actions of these prominent figures. Complexity is the key hallmark of ageing, and is nowhere better portrayed than in these leaders.

Last week, I brushed against several other aspects of the demographic dividend. The occasion was the annual Sidney de Haan Lecture, named after the founder of Saga Holidays. De Haan was a visionary in realising that older people represented a hitherto unrecognised, but important and lucrative market.

As I often make reference to his pioneering work in recognising these practical and important aspects of the demographic dividend, I felt honoured to be asked to deliver the lecture. It was hosted in his native Folkestone which he and his family have supported to a remarkable extent, including the Sidney de Haan Centre for Arts and Health at the Folkestone campus of Canterbury Christ Church University.

A further aspect of the dividend was that among the audience were many older people, including an active 89 year old artist and a 100 year old woman who had recently set up a new company. It is ever good for a gerontologist to have feisty older people in the audience who will invariably ask (as one did in Folkestone!) the key question of what is considered to be “old.”

But recent weeks, through the resignation of Alex Ferguson, had gifted me a further juicy topic for considering the demographic dividend, and one that reaches out to a broad audience. By his deft choice of when to resign, he has also shown that great careers do not need to end in failure.

That his considerable achievements in later life take place in a context of a personality, style, and manner with which many feel uncomfortable is a very realistic way of reminding us that the great achievements of old age remain imbued with all the flaws of younger and middle ages.

Ensuring that we view the rough with the smooth in the demographic dividend is a key principle in avoiding a deadening sentimental romantic view of later life which subverts real and human relationships between ourselves and older people, and ultimately between us as we age and younger generations in the future.

Desmond O’Neill is a consultant physician in geriatric and stroke medicine, and was chair of the council on stroke of the Irish Heart Foundation from 1997 to 2009.