Crammers' Group Ltd is known for its stellar maritime reputation for insuring the transportation of antiques, household furniture and electronics in large supplies. Rebecca, a store owner of Becca's Antiques approached Crammers' Group Ltd to insure her cargoes of antiques valued at US$1M. Rebecca's cargo is slated to be shipped on the voyage from London to Jamaica. Crammers' Group insures Rebecca for the full one million on the strength of her business reputation. Crammers' Group then reinsures its interest with Guardian & Finch, a maritime reinsurance company, to the tune of US$2M.
While en-route from London to Jamaica, 3⁄4 of Rebecca's shipment suffers damage. Rebecca in turn makes a claim on her marine insurer Crammers' Group Ltd for the sum insured. While in the process of gathering the documents to substantiate her claim, Rebecca's friend Nancy Nosey, a maritime broker, uncovers that Crammers' Group Ltd reinsured its interest with Guardian & Fitch. This information she passes on to Rebecca. Rebecca is enraged that Crammers' Group Ltd hid this information from her and attends upon your office. She advises you that she wishes to claim from Guardian & Fitch for the sum 

Crammers' Group Ltd insured for, since they would have used her insurance to 'guarantee the insurance'.
 

As a maritime insurance expert, explain to Rebecca the reason why she is not entitled to benefit from the contract between Crammers' Group and Guardian & Fitch under the principle of marine re-insurance. Please includes at least three case laws