To war with tungsten!
Mr. Corbyn not being in favor of atomic weapons perhaps kinetic projectiles as delivered by ballistic warhead more to his liking? A NON-NUCLEAR OPTION TO DETERRENCE.
Replace the fission and fusion components of the Trident warheads with rods of tungsten. When released on an almost vertical downward ballistic trajectory at an enormous speed [10 kilometers per second] THAT KINETIC ENERGY of the "incoming" immense and prodigious.
Multiple numbers of such tungsten rods as delivered on target by a Trident warhead having the same destructive nature as a tactical nuclear weapon at least.
That size, shape and number [dozens, hundreds, thousands?] of such rods per reentry vehicle I leave to the weapons experts!
"A kinetic bombardment or a kinetic orbital strike is the hypothetical act of attacking a planetary surface with an inert projectile, where the destructive force comes from the kinetic energy of the projectile impacting at very high velocities. The concept . . . originated during the Cold War."
"The typical depiction [as from science fiction] of the tactic is of a satellite containing a magazine of tungsten rods and a directional thrust system . . . The rod[s] picks up speed as it approaches periapsis and the target due to gravity, picking up immense speed until it begins decelerating in the atmosphere and reaches terminal velocity shortly before impact. The rods would typically be shaped to maximize terminal velocity."
"Kinetic bombardment has the advantage of being able to deliver projectiles from a very high angle at a very high speed, making them extremely difficult to defend against. In addition, projectiles would not require explosive warheads, and—in the simplest designs—would consist entirely of solid metal rods"
This image shows London the vicinity of Parliament under attack by kinetic bombardment. NOT nuclear but nonetheless devastating and is meant to be. Mr. Corbyn prefers this?
"The Outer Space Treaty prohibits weapons of mass destruction in orbit or outer space. However, the Outer Space Treaty only prohibits nuclear, biological, and chemical weapons. Since the most common form of kinetic ammunition is inert tungsten rods, in most cases, kinetic bombardment remains legal."
THIS IS DO-ABLE AND ALMOST INSTANTLY SO? Warheads guided with precision to the target by a combination of inertial guidance, GPS, electro-optic and radar.
The big-bang without the residual radiation and heat. Blast however YES!!