The collector, who wished to remain anonymous for fear of 'visits in the night', plans to donate the 200-year-old documents to the National Maritime Museum.
The artefacts, which include pencil sketches of Lord Nelson's State Funeral by painter Henry Singleton, were bought at a local auction for £110, but have since been valued at £10,000.
The collector said: "In my earlier days I was an art dealer and I still collect art. I am particularly interested in Nelson and Trafalgar as it was the greatest military period of the century and as an antiquarian I can't help but be drawn towards the greats of history."
Nelson was buried in the crypt of St Paul's Cathedral on January 9, 1806, after a colourful five-day state funeral.
The unique on-the-spot etchings gives an invaluable insight into the ceremony and shows how an artist collated imagery and notes before embarking on a painting, in the pre-photographic age.
Other items in the antiquarian's collection include a painting entitled 'Admiral Nelson of the Nile and Burnham Thorpe (1798)' by J. Thristle and a pen and ink drawing by Slade Baker. There is also an 1804 Grant of Arms which was issued to William Marsden, who was the First Secretary to the Board of Admiralty during Lord Nelson's time, and found fame after the victory at Trafalgar.
The antiquarian said: "There were huge celebrations in memory of the 200th anniversary of Nelson's death in October, but people forget that he wasn't buried until January.
"It was usual practice to bury at sea all those killed in battle, but Nelson's body was preserved in a barrel of brandy so that it could be brought home and kept as a national treasure."
The sketches can be viewed on the National Maritime Muesum website: www.nmm.ac.uk