Next Friday Liberal Democrats may not be celebrating a great victory, but it will be a lot better than 1970, see https://youtu.be/cq8PMfpA-6g?t=5h40m45s! My prediction that Mr Heath's Government would last no more than 6 months, and that we would regain Orpington, were both wrong.
This time, now that Milliband has definitively ruled out any deal with the SNP, it looks as if there will be a minority Government, and it would be even more likely to suffer defeat in the Commons within six months. But now we have the Fixed Term Parliament Act, early elections can be held only if a motion for an early general election is agreed either without a division or by at least two-thirds of the whole House, or if a motion of no confidence is passed and no alternative government is confirmed by the Commons within 14 days. None of the Parties will be keen to fight another election soon after this one, so when an inevitable defeat does occur, the opposition might then abstain on a confidence motion, depending on what the polls are then saying. The situation would create a degree of uncertainty that doesn't bode well for the economy.