Miss Foster was a Cuban spy. In 1951, she was posted to the Cardington airbase in the United Kingdom to find out about the Dionysus Project. She posed as a Ministry of Defence secret agent who was attempting to determine the identity of the spy. She shot Captain Neil McDonnell, though not fatally, when he discovered her true identity. However, after the project's creator Professor Stone activated the Dionysus machine, Reverend Matthew Townsend overloaded it, tore a rip in the fabric of reality and saw the Divergence. Shortly thereafter, Foster was killed by a bomb which she herself had planted, as were Townsend, Stone, McDonnell and Stone's niece Mary Elson. She had planned to sell the machine to the Communist rebels in Cuba.
While dealing with the aftermath of the explosion of anti-time, the TARDIS created a series of holographic projections, taken partly from reality and partly from the memories of the Eighth Doctor, Charley Pollard and the TARDIS itself. One such projection was the event at Cardington, looking for information on the Divergence. Inside this projection, it placed Charley in the role of a ministry driver and itself in the role of the Minister for Defence. The projection of Foster was created using the image of the Fifth Doctor's companion Nyssa. (AUDIO: Zagreus)