All Creatures Great and Small's Siegfried and Tristan Farnon had 'secret' sibling not mentioned in show

The heartwarming family drama All Creatures Great and Small is set to return with a fresh season on Channel 5 soon, while the channel has been treating fans to reruns of earlier episodes in the meantime.

The show follows the lives of brothers Tristan (portrayed by Callum Woodhouse) and Siegfried Farnon (Samuel West), along with James Herriot (Nicholas Ralph), as they rescue animals at their Skeldale House veterinary practice.

The series draws inspiration from the books penned by Alf Wight, a real-life vet, with characters Tristan and Siegfried modelled after the actual Sinclair brothers, Brian and Donald.

Despite the show's reputation for spreading cheer among its viewers, some of thereal-life characters have endured distressing experiences.

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Brian Sinclair was born in 1915, and tragically lost his father James, a leather manufacturer, when he was just two years old.

Brian had an older sister, Elsa Vaughan, who is seldom mentioned. She tied the knot at St Robert's Catholic Church in Harrogate, with Brian walking her down the aisle, reports the Manchester Evening News.

Elsa became Mrs Cyril Russell in 1934, meaning Brian would have been around 19 years old at the time.

Little else is known about the sister of Brian and Donald, and she doesn't feature in the Channel 5 adaptation of Wight's novels.

In the series, Tristan and Siegfried share a love/hate relationship, accurately reflecting the dynamic between the younger and older vet brothers in reality.

As History Extra elaborated: "The real brothers shared a complex relationship, with Donald often exasperated by his younger brother's laid-back approach to life.

"Brian took a decade to complete his course at the Royal Veterinary College in Edinburgh, and at Donald's expense."

During his youth, Brian had contemplated pursuing dentistry, but developed a passion for veterinary medicine after helping his cousin, who was a local vet.

He was employed by his brother whilst studying and following his graduation, he came back to his brother's practice at 23 Kirkgate in Thirsk, Yorkshire.

All Creatures Great and Small airs on Channel 5