Update 24 March 2020 thank you Gordon Nardell QC for pointing me to R (Merricks) v Secretary of State for Trade and Industry  EWHC 2698 (Admin), most probably the first case to consider the standard of review when an administrative authority applies the precautionary principle.
A quick note on Kenyon v Secretary of State for Housing Communities & Local Government et al  EWCA Civ 302 in which Coulson J checks planning consent ia against the requirements of the EU Environmental Impact Assessment- EIA Directive 2011/92. Of particular interest is his application of the Wednesbury judicial review test.
At 12: ‘A decision as to whether a proposed development is or is not likely to have significant effects on the environment can only be struck down on Wednesbury grounds’. ‘Wednesbury unreasonableness‘ is akin to CJEU standard of judicial review. Diplock J formulate it later as an administrative decision being annulled only if it was ‘So outrageous in its defiance of logic or accepted moral standards that no sensible person who had applied his mind to the question to be decided could have arrived at it.’ The grounds in Wednesbury are very akin to the CJEU grounds: annulment will follow only if (well summarised by Wiki):
- in making the decision, the defendant took into account factors that ought not to have been taken into account, or
- the defendant failed to take into account factors that ought to have been taken into account, or
- the decision was so unreasonable that no reasonable authority would ever consider imposing it.
Applied at issue at 63 ff to the precautionary principle, applicant’s argument that ‘inevitable air pollution caused by the development’ must be taken into account, fails. at 67: ‘In circumstances where there was no doubt in the mind of the relevant decision-maker, there is no room for the precautionary principle to operate.’ (Clearly and in applying all Wednesbury principles, that absence of doubt must have followed from the right information having been taken into account).
EU environmental law (with Leonie Reins), Edward Elgar, 2018, p.28 ff.