Churchill actually delivered this speech in 1943, at Harvard University in Cambridge, Massachusetts. In the alternate timeline, the eastern United States is unavailable to him, and the delayed delivery must take place in another, unoccupied part of the USA – or of the UK.
Alternatively, when Reed says that "Hitler quickly took England", he may be referring to the entire United Kingdom (a common mistake), meaning that Scotland and Wales, too, are under the Nazi's control. (ENT: "Storm Front, Part II")
That all of the UK is lost would certainly fit with the sentences Churchill speaks immediately before the ones we hear Sato play:
- "We have learned to fly. What prodigious changes are involved in that new accomplishment! Man has parted company with his trusty friend the horse and has sailed into the azure with the eagles ... Even elderly Parliamentarians like myself are forced to acquire a high degree of mobility." 
That's the whole background section removed, full of speculation and editorialising. I've instead took the few relevant parts out of it and rephrased them in a much shorter note. -- Capricorn (talk) 21:01, June 28, 2014 (UTC)