Howdy do,
As it stands, the diff feature shows checksums: http://openguides.org/london/?id=Mile_End_Park&version=2&diffversion...
This is not information of relevance to the user and so should be hidden.
Also, the diff links on the List All Versions pages all compare each version to the most recent revision, which means that the top one will always return "Contents are identical"; these links should compare each version to the one preceding it instead. There should probably be a conditional (if version == 1) replacing the diff link for version 1 with something like "original version", or just nothing, instead.