To ask the Secretary of State for Defence what the (a) unit cost and (b) in-service date of the (i) Chieftain, (ii) Challenger I and (iii) Challenger II main battle tanks was. (218236)

The unit costs and historical financial records of the Chieftain and Challenger I are no longer held centrally and could be provided only at disproportionate cost. The unit cost for Challenger II was listed as £3.5 million in 1999.

The in-service dates were Chieftain 1965, Challenger I 1984 and Challenger II June 1998.