After making three separate returns in September 2013, September 2014 and another in February 2015 to commemorate 30 years of "EastEnders" in EastEnders Live Week, Windsor made an unannounced return to "EastEnders" in 2016, appearing in the episode broadcast on 15 January. After this, it was announced that the character was to be killed off, losing her battle with breast cancer. The scenes were filmed in secret in November 2015, following Windsor's personal decision for Peggy to be killed. She said: "Peggy is a character close to my heart but I made the decision a while ago that I need to say goodbye to Peggy once and for all as otherwise she will always be there, urging me to go back and that is something I need to shut the door on. After thinking long and hard about it, I realised that it is time for me and the audience to say our final farewells to the lady who I have loved for many years and I thought that whilst producer Dominic Treadwell-Collins, who I adore, is still in charge I want him to be the one to oversee it. I am grateful that Dominic has accepted my decision and together, since late last summer, we have been secretly plotting Peggy’s last scenes."