Question to the Ministry of Defence:

To ask the Secretary of State for Defence, in which Top Line Budget allocation the costs of the Mark 4A modification to the UK Trident warhead are included.

I am withholding details of the date of the Mk4A component's entry into service, the cost of the Mk4A programme and the progress made to date in delivering the programme for the purposes of safeguarding national security.

The Top Level Budget for the Mk4A programme is held by Director General Nuclear.