Evidently purchasing in cities such as Cario offer a significant discount in purchase price.

What are the rules governing where you can depart from? Do I have to make my first flight within the country of purchase? i.e. Egypt, or can i depart from anywhere within that continent - i.e. UK - or more specifically Heathrow!

I am planning a RTW trip departing Jan 2006 and have a holiday in late Oct in Egypt booked, was hoping to pick up a cheap ticket there and depart from LHR in Jan -> Is this possible?

Any insight would be greatly appriciated.