[Thanks to Lionel Stride of Temple Garden Chambers for providing this case summary]
The EAT (HHJ Richardson) has handed down its decision in Woodward v Santander, which is authority for the proposition that the exception to the 'without prejudice' rule where there has been 'unambiguous impropriety' only applies in the very clearest of cases.
The without prejudice rule renders inadmissible in subsequent litigation evidence of all negotiations 'genuinely aimed at settlement whether oral or in writing' subject to certain limited exceptions. It had been argued that the case of BNP Paribas v Mezzotero  IRLR 508 created a new and wider exception to this rule where discrimination is alleged.
However, the EAT rejected this submission, finding that the rule should be construed very narrowly. Thus, applying the leading authorities, the exception would only operate where without prejudice discussions would act as a cloak for perjury, blackmail or other clear and unambiguous impropriety regardless of the nature of the dispute.