This week’s question relies on observation. There are pictures of the State Opening of Parliament reproduced on:
http://www.flickr.com/photos/25334641@N08
One of the pictures was clearly not taken at this year’s State Opening. There are two giveaways as to why it was not taken this year. Can you identify both of them?

http://www.flickr.com/photos/uk_parliament/2713158495/
is the odd one out. Tony Blair, Michael Howard and John Prescott are all clearly visible at the front of the procession, so come from the days when MH was still Tory leader and TB was still an MP. The former Serjant at Arms, before Jill Pay, seems to be visible.
Is it the one of the Speaker processing to the Lords?
1. The photo is missing the current Serjeant at Arms Jill Pay
2. The Leaders appear to be Tony Blair & Michael Howard
The odd one out must be this one:
http://www.flickr.com/photos/uk_parliament/3072094530/in/set-72157606435204660/
The two clues are:
1. The Queen’s Royal Coach appears to be configured differently from the way it is in the preceding photo
2. The photo is dated 2006!
I guess the second clue isn’t what you were looking for, though!
I would say the picture of the Speaker and MPs standing at the Lords Bar wasn’t taken this year but last year because:
1) A number of MPs are wearing poppies, which was appropriate for last year’s State Opening on 6 November but not this year’s on 3 December.
2) The Serjeant at Arms is still Major General Peter Grant Peterkin, who was succeeded by Jill Pay earlier this year.
Civil and Colin: You are correct that the photograph showing the procession through Central Lobby is an old one, but the Serjeant at Arms appears to be obscured. Jonathan: you are correct in that the second clue isn’t the one I was looking for!
Michael: Congratulations. You win: correct on both points.
And of course Abraham Lincoln is attributed to have said:
“You can fool some of the people all of the time, and all of the people some of the time, but you can not fool all of the people all of the time.”
But he did say in his first reported speech to the Illinois legislature, (January 1837)
“These capitalists generally act harmoniously and in concert to fleece the people, and now that they have got into a quarrel with themselves, we are called upon to appropriate the people’s money to settle the quarrel.”
Perhaps President elect Barack Obama should also recite the very same to the legislature in January 2008? Children take note; a money tree policy is not something new to government.
Ref: Attributed
http://en.wikiquote.org/wiki/Abraham_Lincoln
http://en.wikipedia.org/wiki/Barack_Obama