Buckingham Palace Flypast

[uriahms]

Does anyone know of navigational information for the Buckingham palace flypast that usually takes place on special occasions like yesterday? I mean what radial they use to track exactly over the palace? The weather was bad yesterday so I'm guessing not visual. Am I wrong? I found this on the 1946 flypast.

http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%201115.html