Question:
Which position did John Diamond, Baron Diamond hold in Mar, 1958?

Context:
 John Diamond, Baron Diamond holds the position of Member of the 39th Parliament of the United Kingdom from Feb, 1950 to Oct, 1951. 
 John Diamond, Baron Diamond holds the position of Member of the House of Lords from Sep, 1970 to Apr, 2004. 
 John Diamond, Baron Diamond holds the position of Member of the 38th Parliament of the United Kingdom from Jul, 1945 to Feb, 1950. 
 John Diamond, Baron Diamond holds the position of Member of the 42nd Parliament of the United Kingdom from Oct, 1959 to Sep, 1964. 
 John Diamond, Baron Diamond holds the position of Member of the 43rd Parliament of the United Kingdom from Oct, 1964 to Mar, 1966. 
 John Diamond, Baron Diamond holds the position of Member of the 44th Parliament of the United Kingdom from Mar, 1966 to May, 1970. 
 John Diamond, Baron Diamond holds the position of Member of the 41st Parliament of the United Kingdom from Sep, 1957 to Sep, 1959. 
 John Diamond, Baron Diamond holds the position of Chief Secretary to the Treasury from Oct, 1964 to Jun, 1970.

Answer:
Member of the 41st Parliament of the United Kingdom