The vehicle was bought second hand by John Williams, aged 71, in 1973 for £985 - the rough equivalent of £15,000 today.
He last drove the car in his 20s before leaving it exposed to the elements in his driveway.
After decades of lying dormant, the car went under a three-year restoration at Aston Martin Works in Newport Pagnell, which was completed on Tuesday, December 2.
There were only 1,022 DB5s created between 1963 and 1965. Their popularity was then boosted after James Bond, played by Sean Connery, drove one in the films Goldfinger and Thunderball.
John’s DB5 Vantage in silver birch grey is one of only 39 models in the world. Even in its dilapidated condition before refurbishment, Aston Martin still valued the car at £500,000.
John fell in love with Aston Martins as a child, and had saved enough money to buy one by the age of 19. But after moving to the Middle East for a job in the 1970s, the car went into storage.
It was then left on his driveway to rust. Local children took it as an opportunity to play - often climbing on the car’s roof and bonnet, before being told off by adults.
John and his wife saved £400,000 for the three-year restoration in Milton Keynes. After removing the mouse nest found in the vehicle, technicians spent £2,500 hours on repairs.
They replaced parts and restored features, including the original paint job. Now that the car’s restoration is complete, it has an estimated worth of £1m.
9. Restored Aston Martin
Restored £1m vehicle driving past Aston Martin Works in Newport Pagnell. Photo: Dominic Fraser/Aston Martin Works Photo: Dominic Fraser