The man said he only realised the cards could be worth a lot of money after reading in his local newspaper about a single card selling for more than £6,000.
“I know people always talk about finding treasure in the attic, but in my case that is literally true,” said the man, who asked not to be identified.
“When my son was young, in the late 1990s, he started getting cards and swapping them at school.
“I thought they looked nice and wondered whether they might be a good investment.”
He bought some complete sets from someone in Malaysia through eBay. One set that cost him £300 at the time sold for £75,000 at Wednesday’s auction.
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Rare collection draws global bidders
The 42 sets had been kept sealed in bespoke Pokémon binders and stored in the attic after his son lost interest in the franchise.
Ewbank’s said “jaws hit the floor” when the collection was brought in.
The top lot was the Legendary Collection Complete Master Set, which included a near-mint Charizard card. Estimated at £15,000-£20,000, it sold for £100,000.
“We had bidders from all over the world,” said Andrew Ewbank, who conducted the auction.
“The buzz was incredible, especially because the collectors could not believe how good this collection was – extensive, untouched, complete, and with just about every rarity you could hope for.”
The £1.56 million sale beat the previous record of £872,000, set in London on 9 October.