Originally Posted by alex0683de

Not always. Qantas sometimes has reasonably priced oneways that are definitely cheaper than a return would be. They also have the added advantage that they are also more flexible (should your son have to postpone his departure for whatever reason).

One thing I would look at (call STA for this, they tend to have them on offer) is to get a reasonably priced return ticket with an open return date (which would be valid for a year from date of issue). I know, I know, your son is not planning to return to the UK within that year, but this way you'd pay about the same and still have the option of bringing him home on short notice should that become necessary (illness, a death in the family, missing him at Christmas - there are loads of possible reasons why he might need to come back despite his plans). It'll definitely be cheaper than buying a last-minute ticket in the event. If a full year passes without him needing to come home, then this way may still be cheaper than a one-way and anything you paid extra can be thought of as an insurance premium protecting you against a high-fare last-minute emergency ticket home.