M&S hackers believed to have gained access through third party

Emma SimpsonBusiness correspondentGetty ImagesMarks & Spencer was hit with a cyber-attack in AprilThe hackers behind a cyber-attack on Marks & Spencer (M&S) managed to gain entry through a third party who had access to its systems, the BBC understands.The cyber-attack, which happened in April, has caused millions of pounds of lost sales for M&S and left it struggling to get services back to normal, with online…