Every so often, I read that when Alabama insurance companies refused to insure cars involved in the Montgomery Bus Boycott, Lloyd's of London filled the gap. (Fun fact: Lloyd's has also been known to insure celebrity body parts.) A quick search doesn't say much more on the topic, though I did find a brief mention specifying that the cars of Christian churches were insured.
Can anyone give more insight into the situation? Given that Lloyd's wants to make money, did they charge inflated rates due to the lack of competition and likelihood of violence? Or was there a socially conscientious underwriter? Number of cars involved, total policy worth, any actual payouts?
What happened is that the boycotters were using their own community members' cars to shuttle people around in car-pools and free taxi services, so that no one was left unable to make it to work, school, doctor's appointments, etc, because of the boycott. All of the cars, however, were ensured with local insurance firms, and these firms cancelled policies on boycotters cars in September of 1956, in an effort to help break the boycott.
In order to ensure that the boycotter's cars were insured, and to ensure that they wouldn't be cancelled again, the boycott organizers picked an insurer who they were certain they could depend on. One of the articles I found quotes Martin Luther King, Jr. as stating that "our cars are now ensured by Lloyds of London. We don't expect any more insurance problems."
The important context here is that Lloyds was one of the most famous and without a doubt the most reputable insurance firm in the world at this point - they were well known as a firm which was willing to ensure high-risk, high-value items that other insurers wouldn't look at, and for providing rock-solid coverage. So they would have been attractive to the boycotters both because they were in the UK (there was no way that segregationists would be able to convince Lloyds to cancel their policies) and because there was very little chance that Lloyds would decline to insure them.