Lexus are like every other insurer just brokers, in other words they will sell you a policy which is under written by another company in this case.
Policies are underwritten and administered by Aioi Nissay Dowa Insurance UK Limited. Registered in England, No. 11105895.
Which in turn is one of 5 Japanese insurance companies in the MS&AD Holdings group.
Interestingly Kwik Fit have now started doing car insurance using the same underwriter so it would be interesting to see a comparison quote between them and Lexus insurance.
Another point regarding “comprehensive” insurance is that the actual description is somewhat misleading. If you define comprehensive you find
“including or dealing with all or nearly all elements or aspects of something.”
However this is generally not the case with all the available add ons like protected NCB, driving other vehicles and legal protection amongst many others.
Perhaps 1st Party insurance would better describe a comprehensive policy and paying in Yen would be cheaper.