As ever, when discussing employment policies, we enter a world of complexity where good intentions are bedevilled by unintended consequences.

For example, if older staff hog senior positions for longer periods, younger staff will worry about their promotion prospects.

However, issues such as this are manageable and should not detract from making the best use of the people you have to hand.

The trend elsewhere in the world is not only to push back the retirement age, but for companies to start rehiring retired employees. Much of this is to do with workforce shortages and some to do with governments trying to reduce their pension expenditure, but somewhere in all of this is recognition of the value of experienced people in the workforce.

Nowadays, we see increasing longevity among citizens of more prosperous societies, and they remain highly active beyond the age of 60.

In the interests of full disclosure, I should state that I am of an age where retirement issues are far more pressing than youth training and, as an employer, I admit to a bias towards the employment of older staff.

This bias is based on more than two decades of experience that shows older staff, particularly women, tend to have a very strong work ethic and, of course, a great deal of experience.

By coincidence, this month also saw publication of a report on female managers in Asia. The report, by recruitment outfit Alexander Mann Solutions, found that women managers in Hong Kong were the least confident about their career opportunities, fearing their gender to be a barrier to promotion.

In some ways, this is shocking because the rest of the world seems to have got over the idea that women are less able than men to handle management jobs.

However, even in countries that have quite extensive anti-sexual-discrimination legislation, women remain a distinct minority when it comes to filling the top corporate jobs.

Some see a solution in devising positive discrimination policies, not just for women but also for racial minorities.

In my experience, especially when it comes to women, this idea is viewed with unease because they fear that instead of a focus on their talents and abilities, female employees will suffer the stigma of being seen as having got jobs on the strength of their gender.

This is a well-rehearsed debate and not at all one-sided. However, if the issue of gender discrimination is simply viewed as a matter of business, there surely can be no argument over the value of female executives or indeed of other women in the workforce.

However, there is understandable resistance to this conclusion from men holding senior positions who fear competition from their female rivals.

So we are left with what amounts to little more than a series of prejudices. Nowadays, I find myself sitting on the employers' side of the table, and I cannot deny a degree of prejudice when hiring or promoting staff.

Sometimes you are influenced by their appearance, sometimes by personality traits.

Aside from specific job skills, industry knowledge and other quantifiable aspects of employment, it remains the case that impressions count for a great deal.

Over time, the wisdom of employment decisions is clarified by seeing how employees actually perform in their new roles, but even here some of this assessment tends to be made on the basis of subjective criteria.

There is only a limited amount of science in matters of employment. It is better to be honest and recognise that this is so rather than trying to pretend that total objectivity prevails.

The bottom line is that employing people is complex because people are complex.

When asked what are the most difficult problems of running a business, I always answer with one word: people.

Were it otherwise, businesses could be run by robots, but human intelligence and capabilities confine robots to performing routine tasks, and that's likely to be the situation for the foreseeable future, thank goodness.