The Independent on Sunday newspaper has hired communications research agency, CommunicateResearch (CR) to carry out monthly voting intention surveys in the run-up to the UK General Election.

CR was set up in 2003 by Andrew Hawkins, a qualified barrister who worked for the Harris Research Centre in the mid-1990s.

The company says it will add a “squeeze” question to its IoS surveys in a bid to overcome the problem of respondents who are reluctant to acknowledge support for unpopular parties.

People who say they are likely to vote but do not say which party they favour will be asked who they would vote for if it was a legal requirement to do so.

Tory supporters who refused to reveal their voting intentions led to huge discrepancies between the results of the polls and the actual result in the 1992 General Election.