Question: I've had to book two seprate one way tickets into & out of Iran (a one way ticket from London & vice versa) on different airlines. I just wanted to check if this is OK, in that I wan't have any problems at Heathrow because I only have a one way ticekt on this particular carrier?
Answer: It makes no problem to have no return ticket from Iran. If you have a valid visa your entrance to Iran will be hassle free and your exit documents will not be checked.
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