While the threat of a cyber-attack now features prominently on most U.K. company risk registers, regulatory action so far has been fairly low-key. But a recent case has shown that U.K. enforcement agencies are prepared to show their bite when necessary—and that organisations should take heed.

At the beginning of October, the U.K.’s data protection regulator hit telecom company TalkTalk with a record £400,000 (U.S. $319,160) fine for security failings that allowed a cyber-attacker to access customer data “with ease” (the fine has since been reduced to £320,000 (U.S. $255,328) for early payment).

Neil Hodge is a freelance business journalist and photographer based in Nottingham, United Kingdom. He writes on insurance and risk management, corporate governance, internal audit, compliance, and legal...