Subsea well assembly having a Xmas tree (107, 207) and wellhead (103). From a tubing hanger (113) a tubing extends into the well. A part of a production flow passage extends vertically from the tubing hanger (113) in a vertical bore (111) of the Xmas tree. A fail close production master valve (PMV) (117) is arranged in the production flow passage. The tubing hanger (113) is arranged below the Xmas tree (107), such as in the wellhead (103). The Xmas tree (107) exhibits a branch (115) that deviates from the vertical bore (111), which branch constitutes part of the production flow passage. The fail close type production master valve (PMV) (117) is arranged in the branch (115).