The Guardian's front page, 7th and 8th May 2015
Photo by kind permission of Guardian News and Media Ltd.
© Guardian News and Media Ltd., 2015
The exit-poll prediction at 10pm on election night made for dramatic changes in the story told by the next day's newspapers, such as The Guardian (which evidently went to print at 22:30 on 7 May, having heard only the exit poll, no actual declared results.)
The photo shows The Guardian's front page for 7 May 2015 (top) and 8 May 2015 (bottom).