Dr. Elizabeth Shaw was a scientist at the University of Cambridge, when she was recruited by a United Nations project, she then returned to the University. In the 21st century she was recruited by the same operation, in a classified capacity.
UNIT Moonbase. The dullest place in the world. When she'd been recruited to work for UNIT again she'd been expecting to still be dealing with regular alien incursions and the like. There'd been a few, but mainly she was developing weapons and atmospheric properties to colonise other worlds.
Suddenly a man in a brown suit came in.
"Who are you. I'll get security on you."
"Just wait 5 seconds. Double the thickness of the Dalekanium wires and then they won't explode. Then you'll be able to power the atmospheric generator."
She took a moment to confirm what he'd said. He was right. She got up to thank him, but he was gone. She knew he didn't work there. But he had saved her years of working this out.
If only she'd gotten his name