The MAIB said it was ‘of the firm opinion’ that the yacht had either collided with a P&O passenger ferry, Prince of Bilbao, or had sailed so close that it had been swamped or capsized by the vessel's wash. Accident investigators said the 60-year-old, bridge lookout on the 37,000 tonne ferry was wearing glasses with photochromic lenses which had impaired his ability to see the yacht's lights at night.

The lenses were ‘no more than 80% efficient and, taking into account all of the other known factors, was probably less at the time of the accident’, the report said.

The yacht never appeared on the ferry's radar and the reduced visibility meant the lookout first saw a light from the 26ft boat when she was only about 300 metres ahead.

Michael Hubble, the 61-year-old officer of the watch, who had recently retired and was undertaking agency work, tried a last-minute manoeuvre to avoid the yacht, and believed he had been successful.

The ferry and its crew continued to Bilbao without taking further action.

The bodies of Rupert Saunders, Jason Downer and James Meaby were recovered from the sea following the incident, but no trace of the yacht Ouzo has ever been found.

Watch officer Hubble, from Folkestone in Kent, appeared in court in February charged with manslaughter through gross negligence over the deaths of the yachtsmen.

He was given unconditional bail and is due to stand trial on three counts of manslaughter.