A sketch hand-drawn by Admiral Lord Nelson showing his plan to defeat the French and Spanish navies at Trafalgar has been discovered tucked inside the pages of a scrapbook for nearly 200 years.

The map was found by Nelson historian Martyn Downer in the scrapbook dating from the 1830s which was recently sold at auction.

The drawing was found alongside an address leaf bearing Nelson’s signature and is dated September 5 1805.

Lord Nelson sketch found
A sketch (top left) hand-drawn by Admiral Lord Nelson showing his plan to defeat the French and Spanish navies at Trafalgar which has been discovered tucked inside the pages of a scrapbook for nearly 200 years (Four Corners/PA)

The sketch, which has been donated to the National Museum of the Royal Navy in Portsmouth, shows Nelson’s plan to split his fleet into three divisions to break and destroy the enemy line coming out of Cadiz harbour.

And it includes lines showing the wind direction with Nelson’s plan to attack across the wind, taking advantage of the increased speed.

Mr Downer said: “This fragment of pencil sketch is simultaneously a very intimate and vivid artefact, giving us an exceptional insight into Nelson’s thinking and planning ahead of the battle.

“Its survival is quite remarkable, having been hidden away between the pages of a young lady’s scrap book for the best part of 200 years.”

Lord Nelson sketch found
An address leaf bearing Admiral Lord Nelson’s signature next to a hand-drawn sketch showing his plan to defeat the French and Spanish navies (Four Corners PR/PA)

Professor Dominic Tweddle, the museum’s director general, said: “This is an astounding discovery, it shows that Nelson had thought deeply about how he would defeat the combined French and Spanish fleets long before he ever set foot on HMS Victory.

“We are immensely excited to add this find to our rich collections.”

The plan will initially go on display for one day only on Monday to mark the 214th anniversary of the Battle of Trafalgar before being placed on permanent exhibition from next spring in the museum’s refurbished Victory Gallery.

Nelson was killed on October 21 1805, during his victorious battle against the French and Spanish navies off the southwest coast of Spain.