I had to make a claim on my John Lewis Travel Insurance for a re-routing last year, when there was a brief zika outbreak in Singapore (we found out my wife was pregnant a week before departure). Had to pay to get re-routed from OSL-DOH-SIN to OSL-DOH-BKK.
JLTI didn't question the ex-EU element, didn't care that I was on separate tickets (BA to OSL, QR to SIN). They covered the cost of the re-route and also the pre-booked hotels and other internal flights in Asia that needed changed.