The law of the agreement to arbitrate has divided the English Court of Appeal with C v D and SulAmerica apparently incapable of reconciliation. The latter is, however, being treated by the lower courts (and jurisdictions such as Singapore) as the definitive statement of the law and, in consequence, the substantive law of the contract will generally be the law of the agreement to arbitrate, rather than the law of the seat. Whilst the result in both C v D and SulAmerica is unobjectionable (on the facts both concluding that the law of the seat prevailed), this article seeks to analyse the process of reasoning to reach the results and consider the wider context especially challenges to awards under the 1958 New York Convention. Viewed with that, and other, international contextsthe arguments in favour of the law of the seat are, it is suggested, far more persuasive