Does de-identification require consent under the GDPR and English common law?

Data de-identification has many benefits in the context of the General Data Protection Regulation (GDPR). One of the recurring questions is whether consent is required to anonymise or de-identify data. In this paper, the authors make the case that no consent is required for anonymisation or other forms of de-identification under the GDPR, although additional conditions have to be met where special category data is anonymised. Further, under the English equitable duty of confidentiality, consent is generally not required if the de-identification is performed by the direct care team or on behalf of the direct care team; it is arguable that de-identification can also be performed by others outside of the direct care team, but less clear. The alternative would be special authorisation under section 251 of the National Health Service (NHS) Act.