The nuclear-armed submarine shed thirty per cent of her sonar panels during the mission, not a common sight for the Royal Navy.
A naval source has been reported to say they "have not seen one coming back looking like that before."
The solar panels that cover British subs are designed to absorb sounds, both from the inside and outside of the vessel, masking noise from the boat and absorbing those made by other vessels looking for the sub.
A naval source alleged that the replacement for HMS Vengeance — one of the four Vanguard-class submarines — was possibly not ready, "meaning she had a longer patrol, or she had an incident with fishing nets."
The certification of the ballistic missile submarine and her crew was confirmed the PM Theresa May in January 2017 amid reports of its missile going off course during a test run.
— Sky News (@SkyNews) January 23, 2017
Concerns over operation capability and effectiveness of Britain's nuclear-armed sub fleet have been voiced by Admiral Lord West, a former First Sea Lord, who said the boats were being kept in service for too long.
"All of them are being pushed that little bit more so there have to be concerns. Am I worried about the extending of life and how long it's taking to get the Deadnoughts, the answer is yes," Admiral Lord West said.
The Vanguard-class fleet entered service in the early 1990s and was set to serve for 25 years. Its replacement, the Dreadnought class of ballistic submarines for the Royal Navy is now being built and is not expected in service until the 2030s, which could lead to a worn-out state of the currently operational subs.
— MG Defence Training (@mg_defence) March 20, 2017