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...