Cash has been much in the news recently. Announcements have been made that large denomination notes in the Euro will be withdrawn because they are a favourite of organised crime and terrorists. It’s only a few months since the argument that bitcoin was being used by the same groups. Perhaps someone should remember that “the love of money is the route of all evil”.

Andrew Haldane at the Bank of England called for the end of cash. All the key trends point towards a diminution of cash and cheques in favour of electronic payments. Growth in digital currencies and electronic payment systems, such as Apple Pay, are increasing the variety of alternatives to cash, and electronic payment systems are becoming increasingly convenient. At the same time, in September the FT noted that the UK was hoarding £3bn in cash at home in case of an emergency.

So, how close are we to the vision of a cashless society and what would we need to put in place to realise it? Is it in fact a desirable goal?

Let me illustrate some challenges:

Living in rural England we still get occasional charity collectors door to door. How can I pay if we have no cash? If the system relies on mobile signals to verify payment, sorry but it won’t work here. Over 50% of the time there is no, or very weak, mobile signal.

The farm shop down the road had an “upgrade” to their system from their bank. On installation it failed. For the whole day, only cash payments were possible.

Another neighbour was without phone or internet for nearly a month because of a fault.

In the recent flooding and storms there were many homes without power for days in some major cities of the UK.

Look back to the meltdown of the Electricity Grid in the US North East in 2003. 45 million Americans and Canadians were without power for up to 4 days. This was caused by a software bug on an ageing infrastructure.

Finally, we have had numerous examples of individual bank system failures so that customers have been unable to use ATMs or access their online accounts.

The more reliant we are on any system the greater the need for resilience, universality and a “safe fail”.

I would argue that to build a vision of a cashless society, it is not the cashless technology that is the limiting factor, but the “safe fail” systems to enable the economy to function at a high level of reliability.

For instance, in the loss of the network or power, the ability to transact locally requires retail terminals to be upgraded. The same would be true of say paying for a taxi. What would be the impact on say Uber or Lyft of a major mobile network failure?

Looking at the cashless society from a Critical National Infrastructure viewpoint, I can’t see a credible timescale to make it happen without creating systemic risks.

For a start, imagine if there was a major power failure for London say lasting 24 hours. The power and network infrastructure would clearly be targets for cyberterrorists, even more so than today.

It’s not even just terrestrial challenges. The Royal Academy of Engineering published a report looking at the terrestrial impact of space events such as a solar flare.

With battery life of a smartphone running to a few hours not days, relying on that for payment in the event of a systemic power failure would be problematic.

So, cash may not be King anymore, but it’s not going to be an unwanted relative for the foreseeable future in my book.

So, if serious voices are really suggesting that a cashless society is a “good thing”, there is important detailed work ahead. The current systems for me do not provide the resilience or reliability at infrastructure level or at the application level for the financial system to be safe against shocks.

100% is an unrealistic target for any system of the scale and complexity of payments. However, what is the minimum level we would accept to know that “our financial system is working”?