Poll firm predicts shock losses for Theresa May’s Tories at general election
Controversial YouGov estimate points to hung parliament with 20 fewer seats for My

from The Times (London) – 31^st May 2017

 

 

In hung parliament, the adjective hung means in which no political party has enough seats to secure an overall majority.

The expression seems to have first been used after the general election of 28^th February 1974. The Labour Party won the largest number of seats, although the Conservatives secured a fractionally higher share of the votes cast (37.9% to Labour’s 37.2%). The figures were:
seats for majority: 318
Labour: 301
Conservatives: 297
Liberals: 14
Others: 23
As no party had an overall majority, the incumbent Conservative Prime Minister, Edward Heath, did not resign for three days and explored possible deals with the Liberals and Ulster Unionists. When Jeremy Thorpe, the Liberal leader, rejected the offer of a coalition, Heath resigned and Harold Wilson formed a Labour minority government. (source: Democratic Audit UK)

The earliest instance of hung parliament that I have found is from Tories set sail for early poll, by Simon Hoggart, published in The Guardian (London) of 22^nd June 1974:

The Conservative Shadow Cabinet met yesterday morning under Mr Heath to look for the first time at the party’s draft manifesto. This is not complete yet, but Conservatives are saying confidently that it could be put into action almost immediately, if need be.
The theme they are adopting is one of “national unity” — as opposed to the national confrontation theme which ran through their last campaign — and the first main shift looks set to be in industrial relations. Senior Conservatives now realise that there is no hope of imposing legal coercion here, and recognise that the Industrial Relations Court was an all-round failure.
The big advantage of the marked shift in this field of policy is that the Tories stand to pick up more support from the Liberals — either from the six million people who voted Liberal last time and damaged the Conservatives in dozens of key seats, or from the Liberal Party itself in the event of another hung Parliament. But there is no talk yet of a formal coalition or electoral pact.

The use of hang in the sense to reduce to, or hold in, a state of indecision or inaction was originally American English, especially in the expression to hang a jury, meaning to prevent, as a juryman, a jury from reaching a verdict. For example, the following is from The Indiana State Sentinel (Indianapolis, Indiana) of 2^nd May 1894:

The trial of the Coffin brothers and A. S. Reed for aiding in the wrecking of the Indianapolis national bank has been prolific of sensations, but the greatest was reserved until the last, when it was disclosed that there was on the jury an unprincipled scoundrel who scrupled not to violate his oath and corrupt the stream of justice by attempting to enter into a compact with the defendants to hang the jury for the sum of $5,000, half of this amount to go to the emissary he sent to complete the arrangements.

In hung jury therefore, the adjective hung means unable to agree. The earliest occurrence of the expression that I have found is from The Torch Light & Public Advertiser (Hagerstown, Maryland) of 21^st August 1821:

In Virginia, a jury that cannot agree on a verdict is called a hung jury—thus, when the jury is hung, the criminal is not.