Alex Salmond, the former First Minister of Scotland, who is seeking a return to Westminster as an SNP MP, said he thought the “most likely” outcome of the general election would be a hung parliament in which the SNP kept Labour in office on a vote-by-vote basis. He said that the SNP would expect to have a say on the “vast majority” of the legislation put forward by a minority Labour government — even laws that related only to England and Wales.