After Britain's markets watchdog won a test case against the insurers, insurers have already paid out more than 1.5 billion pounds in compensation to thousands of small businesses that had to close or restrict trading to combat the coronavirus.
However, the test case did not cover all policy wordings, and where they did, some businesses disputed payout levels, resulting in additional court cases.
Stonegate argued in a lawsuit against MS Amlin, Zurich Insurance, and Liberty Mutual that its 760 insured pubs, bars, and nightclubs each faced unique challenges during the pandemic, opening and closing at different times based on regional rules - and seeing business drop by up to 90% below projections.
Insurers agreed that Stonegate's businesses were covered by their policies, but that coverage was limited to a single 2.5 million pound business interruption payment, which had already been made.
According to Monday's decision, there were only two separate events that triggered business interruption payments. Furthermore, Stonegate claimed that it could not file a claim where losses were covered by government furlough payments.
"We welcome the High Court's decision and believe it brings genuine clarity to a very complex business interruption case," said Johan Slabbert, Chief Executive Officer of MS Amlin Underwriting Limited.
"This is a positive outcome for us and is significant to the entire insurance industry... because issues relating to furlough payments and aggregation (total losses over a period of time that are not limited to a single occurrence) in particular have the potential to have a massive financial impact on insurers across the UK."
Stonegate will appeal some aspects of the case, according to an emailed statement from a Stonegate spokesperson, who added that the judgment was "far from conclusive."
"We believe that the court's interpretation on a number of issues that are generally applicable to policyholders is inconsistent with the Supreme Court's approach in the test case and with the approach of courts in other jurisdictions," the spokesperson said.
Separate judgments handed down on Monday in similar cases involving Greggs vs. Zurich Insurance and Various Eateries vs. Allianz also benefited insurers, according to Peter Hardy, partner at law firm Reed Smith, which was not directly involved in any of the cases.
Liberty has refused to comment. Zurich said it was reviewing the Stonegate decision and declined to comment on Greggs.
Greggs' attorneys stated that the Greggs decision "substantially accepts" the sandwich-to-pastry maker's case.
According to Allianz's lawyers, the court ruled "largely in favor" of the insurer. Several restaurants did not respond right away.