New rules that push IT firms providing “critical” services to the U.K.’s financial sector to share more data about cyberattacks and the measures they have taken to maintain resilience have been broadly welcomed by industry experts. However, concerns remain over how suppliers will be classified and how key data might be gathered and shared.

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...