Symington

Mr Symington and Mr Blenkinsop were mysterious men who helped workers at Lexington Bank to have more time. They gave watches, primarily known as Time Harvesters, to their customers, including Andrew Brown, Sameera Jenkins, Nadia Montgomery and many others. They claimed that the interest on them was good.

The Eleventh Doctor discovered their plans when he saw Amy wearing one. He deduced that Mr Symington and his business partner were not who they seemed. After a quick confrontation, they discovered that they were not human; they were actually aliens that resembled sharks.

They could both time travel and doubled over on themselves many times. This meant that there were a number of Symingtons everywhere. (PROSE:  Borrowed Time)