"Thousands of people were deprived of the right to vote last night as polling stations were unable to cope with demand.
"Election chiefs told The Times that the widespread failures to deal with high voter turnout may lead to re-runs in the next few weeks, which could be critical to the overall outcome.
"The Electoral Commission said it would be conducting a thorough review to determine what went wrong.
"An estimated 500 people were turned away in Nick Clegg's constituency of Sheffield Hallam as a large number of students and other voters descended on the polling station at St John's Church in the Ranmoor district of the city. Police had to remove about 100 people who refused to leave."