Defence Expenditure 24. Mr. van Straubenzee asked the Secretary of State for Defence by what proportion of gross national product he expects expenditure on defence to rise during the current financial year. Mr. Pym As a proportion of gross domestic product, defence expenditure according to the NATO definition is expected to increase from 4.9 per cent. in 1979–80 to 5.1 per cent. in 1980–81.