Travel Insurance

There are many excellent travel insurance companies, but the best for your father's England trip is either Trawick International Travel Insurance or Allianz Travel Insurance.

But before selecting the insurance, look for the policies that cover pre-existing conditions, provide adequate medical coverage limits, give you medical emergencies, trip cancellation coverage, and round-the-clock help.

Almost every person opts for travel insurance to safeguard themselves against unexpected events. Since you are going on vacation for 1 month, it's important for you to have travel insurance for your protections. Travel insurance safeguards your finances throughout your journeys. Travel insurance gives you:

Medical coverage in case of medical emergencies, trip cancellation protection, helping you in lost or delayed luggage situations, and many more.

Your travel insurance may cover missed connections, depending on the specific terms of your policy. If your policy covers "missed departure" or "trip interruption" due to unexpected events, then only you can claim for insurance.
To understand better, it's better to talk to your insurer.

For your trip, prioritize travel insurance with high medical coverage in the US, as US healthcare is quite expensive. Choose a company that has a strong international network. The companies which you listed offer travel insurance for the US. But before buying any insurance, compare the quotes, read the reviews focus on coverage, and also know about their claim settlement process for US medical expenses specifically.