Scotland Yard said a post-mortem examination held at Kingston mortuary found a single stab wound on Carole Waugh's body.
Police said further examinations will be made to establish the exact cause of Miss Waugh's death.
More top news
But Jeremy Corbyn said a Labour government would embark on the ‘most ambitious plan to transform our country in decades’.
The firm has pledged to deliver a range of passenger enhancements.
But Nicola Sturgeon said a vote for the SNP would put Scotland’s future in Scotland’s hands.