"Big Ben" was the World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 code name

Code name

A code name or cryptonym is a word or name used clandestinely to refer to another name or word. Code names are often used for military purposes, or in espionage...

 for the British project to reconstruct and evaluate captured German missiles such as the V-2 rocket. On July 31, 1944, after the UK agreed to exchange Supermarine Spitfires for the wreckage of a V-2 in Sweden during World War II, experts at Farnborough

Farnborough Airfield

Farnborough Airport or TAG London Farnborough Airport is an airport situated in Farnborough, Rushmoor, Hampshire, England...

 began an attempt to reconstruct the missile. Also in late July, 1944, Operation Most III

Operation Most III

Operation Most III or Operation Wildhorn III was a World War II operation in which Poland's Armia Krajowa provided the Allies with crucial intelligence on the German V-2 rocket.-Background:...

 recovered V-2 wreckage in Poland that had been obtained by the Home Army

Home Army and V1 and V2

Aside from the military operations, the Polish Armia Krajowa was also heavily involved in intelligence work, including work done with regard to the German "Wunderwaffe" - the V-1 flying bomb and the V-2 rocket...

.