Quick answer

Yes, in defined situations: the without prejudice rule keeps genuine settlement communications out of evidence and does not depend on the label, and it needs a genuine dispute and a genuine attempt to settle rather than litigation already contemplated; the protection generally continues even after settlement, though the material may be admitted for a recognised exception such as whether a settlement was reached or how it is to be interpreted

Yes, in defined situations, and its application to adjudication is still developing. The without prejudice rule keeps genuine settlement communications, oral or written, out of evidence, and does not depend on the label, as Chocoladefabriken Lindt v Nestle shows, provided there is a genuine dispute and a genuine attempt to settle it; the parties need not already be in litigation, as Framlington v Barnetson confirmed. It can fail where there is no dispute, or no genuine attempt to settle, as in Buckinghamshire County Council v Moran. The protection generally continues even after a settlement, and even against a third party, as Rush and Tompkins v Greater London Council shows, but the communications may be admitted for a recognised exception, in particular to decide whether a binding settlement was made and, as Oceanbulk v TMT Asia held, to interpret the resulting settlement. In adjudication, Specialist Ceilings v ZVI enforced a decision where the adjudicator knew a without prejudice offer had been made but had not been shown it, and put that knowledge aside, while in Glencot v Ben Barrett an adjudicator who had mediated and seen without prejudice material created a real risk of apparent bias, so the decision was not enforced.