Such a scenario has long been used to demonstrate the flaws associated with the legacy systems used by banks. The logic goes that if a bespoke application is built by one inhouse developer, there is a risk that noone else will be able to replace or modify the software should that developer leave the bank.

Now a more serious situation has occured in the cryptocurrency world with the exchange Quadriga. 

According to a recent filing for creditor protection made in the Nova Scotia Supreme Court, around C$250m (£105m) of crypto coins are missing  since the death of its founder Gerald Cotten in December.

Cotten had sole responsibility for handling the exchange's funds and his widow, Jennifer Robertson, states in an affidavit that although she still has the laptop he used to carry out  company business, she is unable to open it. 

"[The laptop] is encrypted and I do not know the password or recovery key," she said. "Despite repeated and dilligent searches, I have not been able to find them written down anywhere."

The company has since hired investigators to try and recover the funds but has only succeeded in unearthing a few coins and some limited information from Cotten's phone and computer. 

Quadriga estimates that around 115,000 users have deposits in the form of cash obligations and cryptocurrency, the majority of which was stored in a 'cold wallet' held by Cotten and located offline to secure it from theft or hacking.

The exchange was already experiencing some liquidity problems before Cotten's untimely passing from complications with Crohn's disease while travelling in India. 

In January 2018 the Canadian bank CIBC froze C$25.7m of Quadriga's assets because it was unable to determine the owners of the money.

The company is now looking to appoint auditor Ernst & Young as an independent monitor to oversee the ongoing court proceedings