From TARDIS Index File, the free Doctor Who reference.

Weismuller and his partner Hawk were CIA agents assigned to monitor the progress of an American satellite. When it crashed near Shangri-La in Wales after colliding with a Nostalgia Tours bus, they were assigned to recover it. They were captured by the Bannermen, but freed by Ray, and afterwards they recovered the satellite. (DW: Delta and the Bannermen)