A treasure trove of newly discovered items belonging to William Wordsworth, one of England’s greatest poets, have been given to his Lake District home by his descendants.

The collection includes two portraits that have not been seen for generations and have never before appeared on public display. They were donated to the English Romantic poet’s home, Rydal Mount, near Ambleside.

One of the paintings by Sir William Boxall, a celebrated portraiture and friend of the poet, is the finished version in oils of a study that can be found hanging in the National Portrait Gallery in London. It shows the dramatic image of Wordsworth emerging from a glowering landscape.

The other portrait, a chalk and charcoal drawing by Samuel Crosthwaite, is the last-known portrait of the poet to be made while he was still alive. It shows Wordsworth as a wild old man at the end of his life rather than the more familiar image as a traditional pillar of Victorian society.

For many devotees, perhaps the most startling new arrival is the Wordsworth family Bible, featuring in copperplate writing the date of his parents John and Ann’s wedding day, and the birth and christening dates of all their children, including William and Dorothy.

Wordsworth’s walking sticks, one stamped with his crest in silver, are among the collection and there is also an artist’s impression of a house the poet had planned to build on a nearby field.

The curator, Emily Heath, said it was a “truly astonishing and historic collection”. She said: “Students of Wordsworth and lovers of his life and poetry will find it fascinating. It is a very exciting moment indeed.”

The items have been donated by the direct descendants of Wordsworth, who were keen for them to return to their home and remain in the Wordsworth family.

The poet’s great-great-great-great grandson, Christopher Wordsworth Andrew, said the family decided to give the collection to Rydal Mount after the death of his great-uncle, Gordon Wordsworth.

He said: “Although we were very sad when my great-uncle died, we are very happy that his grandchildren, and my cousins, Giles and Zara Wordsworth, have generously returned these items to Rydal Mount. This was one of the last great collections of paintings, memorabilia and books in my family and it could quickly have been dispersed and lost down further generations. Everything is now preserved for us and the public to view at Rydal Mount.”

They items will go on display at Rydal Mount later this year, marking 250 years since the poet’s birth. A number of events to mark the anniversary are planned in the Lake District and in London, where a wreath-laying service will be held in Westminster Abbey in March.