Defence Evaluation and Research Agency. An agency of the UK's Ministry of Defence, conducting the majority of the MoD's research effort. Under it's evaluation arm, it has many firing ranges, and any kind of testing laboratory you'd care to mention. They are based at a number of locations around the United Kingdom, at some 17 sites. (including Malvern, the site at which I used to work and my home town)

DERA employs about 12,000 people, and has an annual turnover of about £1bn.

Some of the things they've invented that you've probably come across include RADAR and LCDs.

For more info, see http://www.dera.gov.uk