Mr Monaghan, 48, sparked a nationwide hunt when he went missing on 9 January after leaving his home in Solihull, West Midlands. He was found in a hotel suffering from stress and exhaustion.
He was taken to Chelsea and Westminster Hospital where his wife of eight years, Glenna, stayed at his bedside. Earlier in the day she had broadcast an appeal begging him to return home.
Mr Monaghan disappeared after leaving home as normal for work at Railtrack's London office. He called his wife the same day to say he was staying overnight in London, and promptly disappeared.
A West Midlands Police spokesman said: "Mr Monaghan was found safe and well in North London on Friday morning. He was found in a hotel and was identified by the hotel director through a picture that appeared in the press. As a result of that, police were informed."
Staff at the hospital said that the rail executive was in a "serious" condition and needed further treatment. In a prepared statement, Accident and Emergency Consultant Mr Jeremy Booth said that Mr Monaghan's kidneys were failing to function properly. "We have performed a variety of tests, the results of which are causing us some concern," he said. "[Mr Monaghan] would appear to be suffering from a medical condition which needs urgent attention ... As a result we are admitting him to the hospital for further treatment and monitoring."
Last night, relieved staff from Railtrack said they still had no idea why the Mr Monaghan went missing. A spokesman said: "We don't know what's happened, but we are glad Peter has been found and that he is safe. Our best wishes go with him and we hope to see him back at work when he is ready."Reuse content