If it appears at the trial that the destruction of or injury to the property was occasioned or in any manner aided, sanctioned or permitted by the negligence of the claimant, there shall be no recovery. Nor shall a recovery be had unless the claimant used all reasonable diligence to prevent the destruction or injury and shall have, immediately after being apprized of a threat or attempt to destroy or injure his property by a mob or riot, notified the mayor or chief executive officer or chief of police of the municipality or the sheriff of the county, as the case may be, of the facts brought to his knowledge.

L.1951 (1st SS), c.344.