As one of the last surviving Beatles shows us, never give up — not even after five decades:

Paul McCartney is "incredibly grateful" after he was reunited with his beloved bass more than 51 years after it vanished and sparked a global search at the Beatle's pleading.

The 1961 Höfner 500/1 bass guitar — bought by McCartney as a teen in Hamburg for a mere $37 before the fame — was stolen off the back of a van transporting the band's equipment on the night of Oct. 10, 1972, in Notting Hill, according to Höfner executives who launched an investigation into the missing instrument.

The instrument was a regular fixture slung around McCartney's neck during the earlier years of the Beatles' tenure:

It was stolen from a transport truck in the early 1970s, unfortunately, and not seen again — not for a very long time, anyway. But music fans and historical sleuths launched the Lost Bass Project last year in a Hail Mary effort to find the instrument .

The detectives actually managed to track down the original thief, who had lived just near where the theft occurred. That thief told the investigators that he "had sold [the guitar] to the landlord of a pub in the Notting Hill area:"

The pub landlord was Ron Guest, the grandfather of Ruaidhri Guest, who passed the bass down to his sons after his death.

It stayed in the family all those years.

Ruaidhri Guest posted a photo of himself with the legendary instrument, proving its historical authenticity:

Former Beatles sound engineer Ian Horne, meanwhile, was overjoyed to learn that the famous bass he'd lost fifty years before was finally found:

"It was stolen on my watch so to help get the bass back today, I'm thrilled. It's a huge weight off my mind."

Mystery solved!

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