What action is the insurer most likely to take if storm damage to walls was covered under the policy and a garden wall was destroyed?

The most appropriate response in this scenario is that the insurer is likely to meet the full costs of rebuilding the wall less an amount for betterment. In insurance terminology, "betterment" refers to the improvement or enhancement of the property compared to its original condition due to repairs or replacements.

If the damaged garden wall was sustained during a storm, and the policy explicitly covers such damage, the insurer would typically be responsible for the costs involved in restoring the wall to its previous state. However, if the new materials or construction methods would serve to enhance the wall beyond what it was before the storm (essentially providing a higher standard than what was originally covered), the insurer might deduct the amount of this enhancement from the total costs, as they are only obligated to return the insured to their pre-loss condition.

This approach maintains a balance to ensure that the policyholder does not profit from the loss while ensuring that they are made whole again. The other answers suggest actions that would either underpay or deny the claim altogether, which would not align with the principles of indemnity that govern most insurance contracts.