Treason strikes at the very heart of a nation’s survival. Those who knowingly betray their country, aid its enemies, or undermine its security and place every citizen at risk.

Until 1998, the ultimate seriousness of this crime was recognised in law, but Tony Blair’s Government abolished the death penalty for treason that year. There is a strong argument that such an act — deliberate betrayal of the state — should once again carry the gravest possible consequence, both as justice and as a clear deterrent to foreign and domestic traitors.