I can see why this could happen. For instance, I got my Gallbladder taken out last week, there were a few largish stones and the pathology revealed chronic inflammation. I am pretty sure that any recent (less than 2-3 years ) cover would have refused to pay the 270k bill on the ground it was for a preexisting condition. IMHO one should get into private cover in one's early forties, and keep it, to avoid such situations.