As it states, the WP rule will generally prevent statements made in a genuine attempt to settle an existing dispute, whether made in writing or orally, from being put before the court as evidence of admissions against the interest of the party that made them.
Technically, WP communication could be referred to in a grievance decision but if that decision was subsequently required to be disclosed in any tribunal proceedings, then there may be an issue over whether the WP communication within that decision could prevent it from being disclosed or an allegation that WP privilege has been waived, so all such communications must now be disclosed.
Given the potential conflict it could cause to refer to WP communications in open correspondence like grievances, from a practical perspective they should probably be kept separate so there is no doubt about the status of the correspondence. Unless one of the narrow exceptions to WP applies, or the other party agrees to waive privilege (which is unlikely), the disclosure of WP communications in open correspondence could lead to an unnecessary issue over disclosure in subsequent proceedings.
It is also worth considering the spirit of the WP rule. One reason for having the WP rule is the public policy of encouraging parties (or potential parties) to litigation to settle their disputes out of court. The rationale is that settlement discussions (and, it is hoped, settlement itself) will be facilitated if parties are able to negotiate freely, secure in the knowledge that what they have said and, in particular, any admissions which they might have made to try to settle the matter, may not be used against them in evidence should the settlement discussions fail. Although employment tribunals are not bound by the strict rules of evidence that apply in the civil courts, the EAT has confirmed that the WP rule is founded on a "very clear public policy" that applies just as much to employment tribunals cases as to civil litigation, and should therefore be followed (Independent Research Services Ltd v Catterall  UKEAT/279/92)
Call us now on
Partners Employment Lawyers is not a firm of solicitors. Members or Partners Employment Lawyers are consultants at Excello Law Limited and legal services are provided by Excello Law Limited which is authorised and regulated by the Solicitors Regulation Authority under SRA number 512898 https://excellolaw.co.uk/