Astor Management AG v Atalaya Mining PLC

An obligation to use reasonable (or 'all reasonable' or 'best') endeavours, even an obligation to use endeavours to reach agreement with a third party, is generally not too uncertain to enforce because it will almost always be possible to give it sensible content; and a party cannot rely on the non-fulfilment of a condition (here, obtaining a debt facility on which deferred consideration depended) that its own breach of a related endeavours obligation has brought about.