Sorry I can't make this one, chaps.
Also I think High powered lights in St James' Park, bordering Buckingham Palace and Downing Street might not be a good idea unless you really like running very fast from police dogs!!
Can I recommend Primrose Hill? Just above Regent's Park and great views of London at night - really breathtaking! Plus, although the park has lampposts on the paths, just on the west side behind the hill there is a massive area the size of two football pitches - great for testing those throwers! I was up there earlier this week testing out my Javelot. Check out the park on Google - open all night too!
There are several good pubs nearby, lots of restaurants in Camden Town and bus and tube links (Camden Town for tube - bus is the 274 which you can get to and from Oxford st.)
Have a good one chaps.