In 1900, South Africa’s Jimmy Sinclair hit a ball that landed in a train carriage at the Old Wanderers stadium. The train was headed to Port Elizabeth, roughly 556 miles away.
So yeah, there you have it, the longest six ever recorded.
Jokes aside, here's the incident of Albert Trott hitting a massive six over the Lord's pavillion:
Facing the Australian bowler Monty Noble, on July 31, 1899 in an MCC vs Australians match, Trott smashed a ball so high and long that it cleared the entire roof of the Pavilion, soared over the chimney pots, and landed in the garden of the Pavilion clerk on the other side. To this day, Albert Trott remains the only player in history to have ever hit a ball completely over the Lord’s Pavilion. There are numerous source confirming this stroke, including Noble himself.
The center of the pitch at Lord’s is roughly 60–65 meters away from the Pavilion. For the ball to clear the entire building (which is about 20 meters deep) and land in the garden on the other side, the total carry was likely between 115 and 125 meters (pretty big). Reports mention the ball actually clipped one of the chimney stacks on its way down. This suggests it was a towering six rather than a flat one. If it hadn't clipped the chimney, it likely would have travelled even further into the St. John’s Wood neighborhood.
He almost got known singularity for it. He spent the rest of his career trying to recreat it, but in vain.
This might not be the longest six, but when you factor in how thin bats used to be in the 1890s and he did it off a slow-medium pacer, this hit might be more impressive than others.
