A little digging suggests that photo was taken at the end of a six month deployment. Which probably explains the state of the hull - it’s absolutely covered in barnacles & other marine growth.

The crew must have been shattered. Six months is a long time to spend at sea.

Links: https://www.popularmechanics.com/military/navy-ships/a452796... https://www.navylookout.com/royal-navy-nuclear-deterrent-sub...

There's some real staffing and morale problems around Trident, which nobody wants to look too closely at because that would be actual governance. The real purpose of Trident is to threaten left-wing MPs with.