Jim Sillars, who won the 1988 Govan by-election in a breakthrough moment for the Nationalists, said the argument for backing the new independence movement on the list vote was "incontestable".The Scottish political veteran fell out with Salmond in the early 1990s over differences in party strategy and became one of his most persistent critics in later years.But Sillars - who served as a Labour MP in the 1970s before later joining the Nationalists - has now pledged to back his former political