Upvote:0
He cannot travel on an expired passport. He will not even get a boarding card from the airline when checking in (first time he has to show his passport).
Upvote:2
There's absolutely no way. Latest the immigration authority would stop him, he will probably not even be let on the plane.
Upvote:8
Your friend's only course of action is to apply for a new passport (or perhaps another emergency travel document) at the High Commission or a consulate of Pakistan. If it takes too long for your friend's travel plans, there is not much to be done.
Renewal shouldn't take that long. According to the website of the High Commission, regular applications are processed in 20 days, and urgent applications, the surcharge for which is just Β£20 unless the passport was lost or stolen, take 10 days: http://www.phclondon.org/mrp/fees/