Operation Blue Sky was a UNIT operation. It took place in London in the year 2009. It was a raid on the London headquarters of the company ATMOS to discover whether the company was harbouring illegal aliens.
Operation Blue Sky was coordinated by Dr. Martha Jones. It ended in them taking over the company's factory and using it as a base. The ATMOS staff didn't attack or resist arrest. (TV: The Sontaran Stratagem)