If you watch daytime television you may be familiar with the crime series Endeavour, which is about the fictional Inspector Morse as a young detective constable.

The young Morse surprises his boss, Inspector Thursday, by predicting what Mrs Thursday, has put in his sandwiches that day. ‘Cheese and pickle’, Morse announces. And, he’s right.

In fact, it’s not hard to predict what Mrs Thursday has put in the sandwiches. She uses the same filling on the same day each week. If it’s Tuesday, it’s cheese and pickle.

We could call this experience-based prediction. What will happen in the future is what has happened in the past.

You may wonder what this has to do with policing now. In fact, quite a lot.

This is the time of year when the Chief Constable and I sit down and peer into the future.

We have to work out what the demands on the police service will be for the coming financial year – starting in April – to prepare a plan and a budget.

So we ask questions: Will the crimes that people commit next year be the same as this? Or are there different or new sorts of crime emerging?

Answering those sorts of questions often means looking at what is happening in society now and trying to understand what the implications might be for the police in future.

So, for example, we know that we are an ageing society. By 2045 almost 25% of the population will be over 60. Moreover, we are living longer than all previous generations. This means that there will be far more older people next year than even five years ago, and that has implications for policing.

Older people are vulnerable to certain types of crime. These may be crimes that start with opening a door to someone, or they may be crimes committed over the internet.

The latter is a fast growing area because more and more of us use the internet, including older people.

So the questions this raises for policing is: What sorts of crime could follow from this combination of an ageing society and one that uses technology? And what volume of crime might there be?

In turn that will suggest having a certain sort of workforce to tackle them. It’s no good having more PCSOs if you need police staff who can understand how to deal with the cyber criminal.

Unlike Mrs Thursday’s sandwiches, what happened to crime in the past may not be the best guide for the future.