Peacemaker.

This is coolbert:

"Defense Secretary Grant Shapps and First Sea Lord Admiral Sir Ben Key were both on board the submarine during the test, according to the newspaper."

See that most recent blog entry the abortive submarine launch of a Trident missile! 

See too the video of the Trident missile malfunction. Cleared the water, rocket motor fired, then gyrations and catastrophic failure!

Too what extent the British submarine and crew were in peril from their own missile I guess will be a question that should never be asked or answered if indeed asked!

VIP onboard of the most highest level of authority and rank "observing" the launch I can only guess what their response was.

Do not think such a calamitous event existing in a vacuum. Historically such debacle during weapons testing or demonstrations not common but not rare either.

Naval gun of the "Peacemaker" variety exploding, killing numerous very high-ranking American VIP the USS Princeton [1844].

"On February 28, 1844, during a Potomac River pleasure cruise for dignitaries, one gun exploded, killing six people including Secretary of State Abel P. Upshur and Secretary of the Navy Thomas Walker Gilmer, and injuring others, including a United States Senator and Captain Stockton. The disaster on board the Princeton killed more top U.S. government officials in one day than any other tragedy in American history. President John Tyler, who was aboard but below decks, was not injured." 

See also this prior blog entry item # 2 a live and armed torpedo mistakenly fired at a warship on which as an observer no less personage than the USA President Franklin Roosevelt.

Think also from the era of the Cold War the event referred to as the "Nedelin Catastrophe". Soviet liquid-fueled intercontinental ballistic missile undergoing test  a major malfunction occurring. Marshal Nedelin perishing along with numerous other VIP and observers present. 

Thankfully this British missile firing submarine escaping calamitous damage. But always, take precautions!

coolbert.