comprehensive car insurance cover others not on the policy?

comprehensive UK car insurance. Can I drive his car and be covered by the insurance even though I am not listed on the insurance and live at the same address. I have a full UK license, he claims I am covered because he gives me the permission to drive the car which according to him is right.
I have read the insurance policy but my brains are not big enough to understand that "given permission" part.
If anyone can throw more light on this, it will be fully appreciated.





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