Warning bells starting chiming as soon as I read how much the insurance cost. He might not have known better, but £273.70 for 18 months of insurance is at least 10x too low.

My trick is simple: Get an Amex Platinum if you need insurance for under 2 weeks [1] and buy insurance from your bank for anything longer. Banks compete on trust, so they don't randomly fuck you over. I actually used my bank's health insurance when I needed it and they were nothing but professional. It was RBC Canada, if it matters.

[1] Reach out to me if you do this and we'll both get enough points for a free transatlantic flight.