For years, a British man watched bitcoin’s price rise while believing his investment in the cryptocurrency had been lost, beyond his reach.

He bought his first bitcoin back in December 2011 through Britcoin, a U.K. exchange that later became Intersango. The exchange stopped trading in late 2012, before going offline by early 2014.

“The worst thing was seeing Bitcoin grow and knowing what I could have done with the money,” said the man, identified only through the pseudonym “Chris.”

His initial investment was of around 1,500 pounds ($2,000). His holdings rose to $5,400 before Chris lost access to the funds.

“When I lost access to the wallet it was a big shock and quite devastating, because we weren’t in a great financial position,” he said. “I had a young family, a new home and it was money I couldn’t afford to lose. “

Law firm CEL Solicitors, using crypto-tracing software through its sister firm The Crypto Tracing Experts, identified a wallet believed to belong to Intersango users, with more than 5,500 $BTC ($421 million) in it.

The recovered funds, according to the law firm, appreciated to the point the funds are now worth $4.5 million. At the time of purchase, the firm said, Chris bought below $4 per $BTC, with the cryptocurrency now trading at around $76,500.

The recovery turns an early crypto investment that appeared lost into money that could help his family buy a larger home and pay down debt. Chris said he plans to keep some of the bitcoin despite concerns about price swings and theft.

“I can help my son pay off some of his loans on his new house,” Chris said. “I want to keep some Bitcoin to see if the value rises again but if I do it does make me nervous in case it goes down and although some investments are more regulated now, crypto isn’t. “

The case may have wider consequences.

Ryan Sweetnam, director of financial litigation at CEL, said recovering the assets required records showing that clients had bought the bitcoin, including bank documents dating back almost 15 years.

The firm said other former Intersango users may also be able to recover funds if they can establish ownership.