LONDON—A top British government official is backing a phone company’s proposal for a new tracking service to help protect women walking alone, an idea pitched amid ongoing outrage over the slayings of two young women who were targeted near their homes in London. The chief executive of Britain’s biggest phone company, BT, proposed the “walk me home” service in a letter to Home Secretary Priti Patel. Once a woman activated an app on her phone, the service would track her journey and send an alert to her emergency contacts if she didn’t reach her destination on time, Philip Jansen said in the letter. The UK Home Office confirmed Patel had received the letter and would respond in “due course.” Patel was more supportive in comments to the Daily Mail. “This new phone line is exactly the kind of innovative scheme which would be good to get going as soon as …