It is not just growth-oriented London-listed investment companies, such as Scottish Mortgage Investment Trust plc, that have fallen in value by around 50 percent over the past six months. Bitcoin, the best-known cryptocurrency, has experienced a similar fall as has Etherium.

But this has not deterred cryptocurrencies’ cheerleaders - or their public relations firms - from extolling the virtues of this particular form of money or its potential as an investment asset.

A day ...