Badly fitting manhole cover, raised edge, trip hazard

Manhole cover on footpath adjacent to the end wall of 30 Spruce Gdns, NG6 7DH (Severn Trent Water?) is raised about 20mm on one edge and presents trip hazard. I witnessed a member of the public walking south on this pavement trip and almost fall today. Though he had lightly twisted his ankle, he declined to leave his details or make a report. He was young and fit, it could have been far more serious for an older person. As far as I am aware, the cover has not been opened recently. I walk this path several times most days and have never actually noticed the problem before.