I will be in London on 16th June and am looking for something to do related to the Queen's Diamond Jubilee.
Does anyone have any suggestions, or perhaps a web address with an authoritative list of events?
DirectGov and the British Monarchy have both published lists of events for the Jubilee. Alas, the events seem to mainly be a couple of weeks before you get there:
The Official Website of the Diamond Jubilee also has more information.
However, this doesn't mean there won't be stuff to do. Indeed, if you look at the Public Services website above, there are special exhibits on at many museums and galleries, no doubt Buckingham Palace will be doing something, and several trusts are also organising events, creating new woodlands and more.