Actress Sheila Hancock travelled to Haworth to make a new documentary about the Bronte sisters, and made an “important new discovery” among the love letters written by Charlotte to her married tutor.

The discovery will be revealed in Perspectives: Sheila Hancock – The Brilliant Bronte Sisters, to be screened on Easter Sunday.

Miss Hancock, the widow of actor John Thaw, said she was passionate about the Brontes’ work.

“I have been a fan of the Brontes since I was a child,” she said. “I think all three sisters are brilliant and I don’t have a favourite.

“All reading their work does is put me off writing my own novel. Their work is wonderful and one couldn’t hope to aspire to be as good as that.”

In the programme she investigates what inspired the siblings, and starts her journey in Haworth, where they grew up, before travelling to other places important to the family, including Brussels, where Charlotte worked as a governess, and Scarborough, where Anne died from tuberculosis after being taken there to convalesce.

The documentary tackles the myth that the Bronte siblings were isolated country folk, and looks at how Charlotte was partly responsible for this misconception after her siblings’ early deaths.

Miss Hancock looks at the unconventional education that led the girls, along with their brother Branwell, to write from an early age, creating imaginary worlds inspired their later work.

Delving into the work of the literary family, the actress sets out to discover what inspired them to write such epic novels in the mid-19th century.

Miss Hancock looks at Charlotte's love letters to her married tutor Constantin Heger, visits the National Portrait Gallery to see the only surviving painting of the sisters together, and takes a journey to Anne’s clifftop grave in Scarborough.

The programme is on Sunday on ITV at 10pm.