UK GDPR Article 5 says personal data must be “kept no longer than is necessary.” But who defines necessary?

The UK GDPR says don’t keep data longer than needed. But what does that actually mean in practice? UK GDPR Article 5 says personal data must be “kept no longer than is necessary.” But who defines necessary? Interpretation depends on: There’s no universal timeline — only justifiable ones. If your retention lacks clear purpose or…