The lockdown measures imposed by the Health Protection (Coronavirus, Restrictions) (England) Regulations are some of the most extreme restrictions on fundamental freedoms imposed in the modern era. They are a disproportionate interference with the rights and freedoms protected by the European Convention on Human Rights and therefore unlawful.
This is an executive summary of a more in-depth article which is available from the link below. Inevitably, the summary simplifies the detailed arguments and considerations.
Read the article in full: A disproportionate interference with rights and freedoms: Coronavirus Regulations and the ECHR