The keel laying ceremony of HMS Dreadnought, on March 20, was a largely symbolic act. Firstly, submarines don’t actually have a keel. Large parts of the submarine were also present in the facility during the ceremony. This is because the first steel was cut for HMS Dreadnought on October 6, 2016.
Since that time, 16 separate modules have been built for the submarine. These will be welded together. The vessel will then be fitted with the Rolls-Royce nuclear reactor and other key parts. So, in truth, the keel laying ceremony really marks the start of the final assembly of HMS Dreadnought, rather than the start of construction.