These images were emailed from an unknown "Kiwi Joe," who might be anyone. The message indicated that they were taken at the March 26, 2011 "anti-cuts" demo in London, but suppressed by the media.
However, according to this report from August 2006, which includes the same photographs:
Almost all of the photographs (that we saw) are copyright to the Associated Press. They were taken in February , in London, during a demonstration against the Danish cartoons depicting the Prophet Mohammad. They were taken near several different European embassies in London -- not yesterday [i.e., not on August 26, 2006] -- and not at a "Religion of Peace Demonstration" [April, 2006].
Moreover, the claim that these pictures were not published by the media is false. The San Francisco Chronicle, for example, used three of the pictures in an item on the February 3, 2006 protest march to the Danish embassy in London. There it is reported that:
As the result of separate trials, Mizanur Rahman, Umran Javed and Abdul Muhid were each sentenced to serve six years in jail "for soliciting murder and three years concurrently for stirring up race hatred." A fourth man, Abdul Saleem, "was cleared of soliciting murder...but convicted of inciting race hatred" and was given a four-year jail sentence.
The San Francisco Chronicle item references this illustrated article in the UK's Daily Telegraph, and this illustrated report by the BBC.
Evidently these photos have been circulated with a false attribution on more than one occasion. By whom and why, whether by individuals acting independently or as part of an organized campaign would be interesting to know.