The FAA can give you the definitive answer
http://www.faa.gov/other_visit/aviat.../info08012.pdf
Re Tom Hughston
For the avoidance of doubt:-
I've never met or corresponded with Tom and have no axe to grind either way.
Any Googling on this subject will turn up lots of stuff. Here's a short history of my own involvement.
AOPA UK made enquiries some months ago of the FAA Head Office and were given information which it published in good faith. That information stated that a personal vist to a FSDO was required. Tom and his suporters objected strongly to what AOPA published but did not provide any definitive information to support their contention that 61.75's and English Proficiency endorsements could be obtained through DPE's (Designated Pilot Examiners).
I researched the situation and found the references that I have referred to on this thread. The information was then posted on the AOPA UK thread at
AOPA UK • View topic - FAA throws a spanner in the works
If the information regarding Tom not operating at present is correct then it may be that he's fallen foul of the restrictions contained in Art 140 of the ANO
Restriction on aerial photography, aerial survey and aerial work in aircraft registered elsewhere than in the United Kingdom
140 (1) An aircraft registered in a Contracting State other than the United Kingdom, or in a foreign country, shall not fly over the United Kingdom for the purpose of aerial photography or aerial survey (whether or not valuable consideration is given or promised in respect of the flight or the purpose of the flight) or for the purpose of any other form of aerial work except with the permission of the Secretary of State granted under this article to the operator or the charterer of the aircraft and in accordance with any conditions to which such permission may be subject.
(2) Without prejudice to article 93 or to paragraph (1), any breach by a person to whom a permission has been granted under this article of any condition to which that permission was subject shall constitute a contravention of this article.
And of course to do it in a G-Reg would require the appropriate JAA or CAA license to be held.