The Avro Z-59 was basically a Blue Steel with a nuclear ramjet mounted on top. Solid rocket motors would propel the missile to a speed when the ramjet would light. It would then travel at low level at Mach 2, leaving a radioactive plume behind it. Once at the target, the nuclear warhead would detonate, adding the reactor material to the fallout. Nasty!
This image can be found in Chris Gibsons' excellent book, Vulcan's Hammer: V-force Aircraft & Weapons Projects Since 1945 (Consign).