Norwich Union and Zurich this week appeared in the House of Lords to argue that sufferers of pleural plaques should not be entitled to compensation.

The insurers’ appearance before England’s highest court marks the final stages in the long-running dispute between trade unions, claimant lawyers and the insurance industry over whether pleural plaques should be compensable.

Pleural plaques attach themselves to the lungs and are believed to be caused by exposure to asbestos.

They are symptomless, have no adverse effect on any bodily function and, being internal, have no effect on appearance

The Court of Appeal ruled in January 2006 that plaques should not be compensable. But leave to appeal to the House of Lords was granted, as the appeal court judges were not unanimous in their decision.

Claimant lawyers argue that there is a higher incidence of mesothelioma in individuals with pleural plaques and compensation should stem from the stress of knowing this.

Insurers argue that the development of mesothelioma has nothing to do with the existence of plaques but is connected to the original exposure to asbestos. On that basis plaques should not attract compensation.

A decision is expected no earlier than October. If pleural plaques are ruled to be compensable then argument will focus on the level of damages.