§ Mr. Simpson
To ask the Secretary of State for Defence, pursuant to his answer of 13 January,Official Report, columns 128–29, for what reasons the operating costs of Polaris (a) fell in the financial year 1984–85, (b) rose in the financial year 1985–86 and (c) fell in the financial year 1988–89. 
§ Mr. Soames
Details of calculations pertaining to the 1980s are no longer available. Annual cost changes would have resulted primarily from the operational and maintenance cycles of individual submarines.