Is the State Immunity Act 1978 the sole basis for deciding on State immunity? It is and it is not. This seemingly self-contradictory reply is due to the fact that, on the one hand, any proceedings directly or indirectly against a foreign State must be brought under the 1978 Act while, on the other, certain provisions of that Act might paradoxically render the Act itself inapplicable and therefore entail recourse to rules outside the Act for settling the issue of State immunity. This is amply illustrated by the decision of the House of Lords in Holland v. Lampen-Wolfe [2000] 1 W.L.R. 1573, which involved a claim for defamation brought by a US university professor teaching international relations at a US military base in England as part of an education programme provided by her university under a commercial agreement with the US Government. The claim was brought against the education services officer at the base, who had written a memorandum listing serious complaints about the plaintiff’s performance and questioning her professional competence. The US Government claimed immunity on the defendant’s behalf.