HMS Courageous is steaming when the explosion occurs. The next shot show Courageous dead in the water. There's no way a 65,000 ton ship comes to a dead stop like that.
New Ambassadors do not present their credentials at Buckingham Palace as mentioned here. They are formally, by tradition, accredited to the Court of St James, at St James's Palace., which was in use as the official royal residence long before Buckingham Palace was built.