The solution he adopted was to steal an identity.
The baby born in Sunderland in 1950 whose name was John Jones died in infancy. Babies who died before the registration of deaths and births was digitally integrated into a single system present a particular vulnerability: their names exist in birth records but not in death records, making it possible, with the right research, to obtain documents in those names as if the person had survived to adulthood. This practice—sometimes called “ghost identity” fraud—has been used by various criminals over the decades, and the John Jones approach was a documented instance of it.
Darwin obtained a passport in the name of John Jones. The exact date of this application and the supporting documents used to obtain it are not fully detailed in the available public record, but the fact of the fraudulent passport is confirmed by the charges against him: one of the counts to which he eventually pleaded guilty was the passport offence.
Under the name John Jones, Darwin could travel. He could hold a passport. He could present himself to foreign bureaucracies as a person with a documented identity. The alias gave him a kind of official existence that his own name no longer provided—because John Darwin, officially, was dead.
He also used the alias “John Williams” at some point around 2005. An angler encountered a man using that name near Penzance, Cornwall, in May of that year. The encounter did not trigger any alarm at the time; it was only in retrospect that it became part of the reconstructed chronology of where Darwin had been during his years of supposed death.