(a)  For a contract to be frustrated, the circumstances which affect how performance is carried out must have changed, without the knowledge of the parties, before the contract is entered into.

(b)  For a contract to be frustrated, performance need not be completely impossible - it is enough if the changed circumstances make performance materially different from what the parties originally envisaged.

(c)   Even if performance has become impossible, a contract will not be treated as frustrated if the impossibility has been brought about by the party who wants to be excused from performance.