After further consultation with meerkats, opera singers and a supermarket* (money variety) I found £83 as being the cheapest from a known company - luggage/cancellation cover is minimal but medical with the declared conditions covers the usual £15million or so.
*another supermarket, TESCO, by chance sent me a Clubcard "Offer" yesterday for, among other things, travel cover . . . £436 for 10 days !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!