Pro-secession parties at Holyrood have backed a formal request for another vote on leaving the UK The newly elected Scottish Parliament has supported a formal request to London for permission to hold a new referendum on independence. Scottish voters rejected the previous attempt to leave the United Kingdom during a 2014 referendum, which unionist politicians described as a “once in a generation” opportunity. The latest push has been strengthened by recent elections in Scotland and elsewhere in the UK, boosting regional pro-independence movements and delivering a major setback to the Labour Party. How strong is Scotland’s push to quit the UK? The independence movement was only modestly weakened by the result of the 2014 vote and gained renewed energy after Brexit, which most Scottish voters opposed in 2016.…