William Pratt
William was a puffy-haired young man in a brown suit. He was a poet, but most people did not like his poetry; some called it "ghastly".
William met the Eighth Doctor and Anji Kapoor in England of the 19th century. He was attending a seance together with several other people who had all lost someone in their lives. William told Anji about his poetry and mentioned that he wondered if Anglo-Saxon races were too pragmatic for genuine enlightenment. Anji didn't listen to his words but pretended to do so and smiled politely when William had said something.
One of William's poems was about ghosts in which he called them "pale ether-shrouded wanderers". He wanted to tell his poem to the people at the seance but was stopped by Mrs Hemming.
Then the seance started. William wanted to talk to his mother but was told that she wasn't there. Then a voice appeared who knew about Fitz Kreiner's time travels and told everyone about it. When the voice told everyone that there would be a terrible war, William got out of the room and escaped. (PROSE: Camera Obscura)
Behind the scenes
William is a reference to the human self of the Buffy the Vampire Slayer main character Spike (played by James Marsters). Spike's human self had the nickname "William the Bloody Awful Poet". He lived in England in the 19th century and wrote poems, which weren't liked by the people. He spoke about his poems a lot and people did not like to listen to him. In Buffy flashbacks he had puffy hair and wore a brown suit and had a very close relationship to his mother.
Although there are several other references to Buffy as a fictional series throughout the DWU, this is the only one to imply any form of crossover between the two.