Chevaline, Poseidon, and the alternative of another submarine

The discussion compares developing Chevaline with obtaining the American Poseidon missile. Poseidon's larger number of warheads and established American support had attractions, but the cost of adapting British submarines also had to be considered. A separate alternative was to spend the money on another deterrent submarine. The reading questions whether Britain had chosen the best balance between improving each missile and enlarging the force carrying them. The full cost of the alternatives is not established, so the comparison does not yield a settled procurement verdict.