But perhaps even more astonishing was what he uncovered next.
Mr Drake, who found the cobweb-covered coffin cover propped up against a longcase clock after climbing through a hole in the wall of the house - the only way in during refurbishment - also helped bring to light the long-forgotten tale of one of the most extraordinary British adventurers of the 20th century.
In fact, it was when he checked the bottom drawer of a canterbury on August 15 that he was also removing from the house that he discovered an LP recording of the legendary Tiger Sarll's (1882-1977) appearance as the subject of This Is Your Life with Eammon Andrews.
"I felt like Indiana Jones uncovering the treasures of the lost temple," Mr Drake told ATG. But, as he soon discovered, Sarll's story made Indiana Jones look quite pedestrian.
The family clearing the house were Sarll's descendants, who still had the Big Red Book from his appearance on This Is Your Life - although they were unaware of the recording - and it told an amazing tale, which was also recounted in Adventurer Extraordinary: The Tiger Sarll Story (1961), by Godfrey Lias.
Born Thomas Henry William Bang-fee Sarll, he originally trained as a doctor and enlisted in the South African Light Horse in 1899 to fight in the Boer War, where he lost the sight in one eye. He later went on to become a big game hunter before joining the Canadian Dragoons, then returned to England to become an actor in early films.
By 1907 he had also tried his hand at journalism before leaving for Morocco and then Argentina, where he helped lay railway track, moving on to Mexico for the revolution in 1910 and then, in 1912, heading for the Balkan War as a cameraman for British newsreels. Despite being sacked from this position, he secured another post filming in Belgium at the outbreak of the First World War.
Following the Armistice he returned to Morocco to report on the rebellion against the Spanish before returning to Mexico where he spent his time capturing pythons and alligators for zoos (at one point he even learnt how to wrestle crocodiles).
This led to him creating a circus act handling snakes and alligators on his return to the UK.
He reportedly ended his career as a security officer at a nuclear power station.
At 6ft 3-4in, he was noted for dressing in spats and a monocle and was reputed to be able to drink a pint of beer while performing a one-handed handstand.
According to the This Is Your Life blog Big Red Book, Sarll, who was surprised by Eamonn Andrews at The Savoy Hotel, failed to recognise one of his own children on the programme.
The coffin cover is just one of the accumulated treasures Sarll is thought to have brought home from his travels and will appear in Willingham's September 13 sale with an estimate of £2000-3000.