You are a claims handler for CD DAC, an insurer. One of your policyholders, WTX Ltd, are the owners and operators of a water taxi. WTX Ltd's insurance policy with CD DAC contains a non-contribution clause. WTX Ltd decided not to renew its insurance policy with CD DAC and arranged for a new insurance policy with another insurer, EF DAC. The insurance policy with EF DAC includes a rateable proportion clause. The insurance policy with EF DAC began on the same day as the policy with CD DAC expired. On the date when the insurance policy with CD DAC expired and its insurance policy with EF DAC began, the water taxi was involved in a collision with another boat. WTX Ltd has claimed against both insurers for the damage to the water taxi. Both insurers decline the claim. 

a) Discuss the extent to which WTX Ltd are insured. Refer to one relevant case in support of your discussion. 

b) Discuss the legal implications for WTX Ltd of an insurance policy having a non contribution clause, rather than a rateable proportion clause.