A previously unknown letter containing a dramatic account of the capture of Australia’s most notorious bushranger Ned Kelly 133 years ago has been donated to the State Library of Victoria.

The letter was written by Scotsman Donald Gray Sutherland to his family on July 8, 1880, and gives great detail about the bushranger soon after the siege at Glenrowan in north east Victoria.

Sutherland’s descendants have handed the letter to the State Library where it has been described as a significant addition to the Kelly story.

“He was wounded in 5 or 6 places, only in the arms and legs – His body and head being encased in armour made from the moule (sic) boards of a lot of ploughs,” the letter reads.

“The force of the rifle bullets made him stagger when hit but it was only when they got him in the legs and arms that he reluctantly fell exclaiming as he did so I am done I am done.”

A lock of hair from Ned Kelly’s horse was enclosed with the letter.

Sutherland noted the horse was Kelly’s “favourite mare who followed him all around the trees during the firing. He said he wouldn’t care for himself if he thought his mare safe”.

Sutherland sailed to Australia in 1876 when he was 24 and worked at the Bank of Victoria in Oxley, 13km from Glenrowan.

State Library of Victoria chief executive Sue Roberts says it’s a remarkable document.

“This letter is a very personal account of events that have become part of Australia’s folklore,” she said.

“It will join Ned’s armour, Jerilderie letter and other important items in our Kelly collection – one of the largest and most significant in the world.”

The letter will be on display in the State Library’s Changing Face of Victoria exhibition from Monday.

It can also be viewed online with a full transcript on the State Library website.