Historical version 2 of St. James' Park (view current version)
A central London park which has impressive views of Buckingham Palace to the West. It has a lake in the middle with birdlife including geese and swans.
Traditionally, this has been the meeting point for fictional spies, who would choose to sit on a bench feeding the ducks and exchange a few coded phrases and their briefcases before returning to their respective Whitehall departments or foreign embassies. -- aegidian
The nearest tube is unsurprisingly [St James Park Station]? but you can easily walk to a number of other stations nearby including Victoria Station or Westminster Station