A joke to make Marcus Brigstocke faint

Here's a joke I heard the other day. 

I think I heard it on the News Quiz, though I could be wrong. I have a vague memory of Jeremy Hardy telling it, Marcus Brigstocke fainting, Sandi Toksvig being carried out on a stretcher and Mark Steel spontaneously combusting. Poor Jeremy had lost the room (well, it was a BBC studio audience, and you know what they're like!) 

Of course, I could have dreamed all that. 

Still here's the joke:

The wife and I decided to take an organised trip to Afghanistan to see for ourselves what the place was like. 

It didn't start well when the train we were traveling on broke down a few miles north of the capital. 

What a third world shithole! Streets full of angry bearded types glaring at us and the Mrs stood out in her sundress as all other women had head-to-toe burqas.

"We are so dead!", I thought.

Anyway, Dave the organiser suddenly remembered that Finsbury Park had a tube station, so we were able to get safely to Kings Cross and on to Kabul from Heathrow.

(Source)