The MIA 1906, s.78(4) provides that it is the duty of the assured and his agents, in all cases, to take such measures as may be reasonable for the purpose of averting or minimising a loss. In many cases the statutory duty will be unimportant, since rights, duties and liabilities declared by the Act or implied into marine insurance contracts by law may be modified by agreement, and many contracts contains a sue and labour clause which effectively reproduces and/or to modifies the statutory duty. The effect of such contractual provisions will, of course, be a matter of construction, though modern sue and labour clauses tend to reflect the principles contains in section 78. However, it must not be assumed that the terms of all contractual sue and labour clauses are, or will remain, identical, either with each other or with the statutory duty. The purpose of this study is to clarify the ambit of sue and labour.