A ticket collector noticed that their tickets were only valid to Luton, in Bedfordshire. But when he challenged the pair, they ran off.
After media appeals, the wife of a Liverpool taxi driver contacted police to confirm that he had driven the children back to Luton last night. The girl was able to pay the driver in cash for the fare, which was believed to be about pounds 180.
Detective Chief Inspector Phil Barr said: "The children got into a taxi in Lime Street and asked to be taken to London. The driver said he could not do that but took them to the taxi office.
"The girl rang her mother from a phone box there and put her on to the taxi driver. The mother confirmed that he should drive them home and that her daughter had enough money to pay the fare.
"When they got there, the children asked to be dropped in Luton rather than at a specific address, and the girl paid the taxi driver. We are satisfied that it is the same two children and that they are now in Luton.
"But we are unable to trace who they are, and we have spoken to our colleagues in Bedfordshire constabulary to try and ascertain who they are and that they have returned to their mother.
"It is a bizarre story, but they are all the facts we have. We still don't know why they travelled all the way to Liverpool or why they had all that money with them in the first place."Reuse content