Lambert v Co-operative Insurance Society Ltd [1975] 2 Lloyd’s Rep 485 is an English contract law case concerning misrepresentation.

It is an example of the operation of a positive duty of good faith in contracts for insurance.

Mrs Lambert signed a proposal form for ‘All Risks’ insurance over her husband’s jewelry, without mentioning her husband was convicted previously of receiving 1730 stolen cigarettes and was fined £25.

Mr Lambert was convicted of two more dishonesty offences in 1971 and sentenced to 15 months jail.

In April 1972 some items worth £311 were lost or stolen and the Co-op refused on the basis of a failure to disclose.