Bus from Heathrow to Oxford

I took a bus from Heathrow to Oxford. The cost was Pds 15 for a single trip. When I returned, I paid another Pds 15.

I asked the driver what was the return fare. It was Pds 18. So, I paid Pds 12 extra by buying two single tickets.

Lesson: ask about the return price, before you start the firt leg of the journey. If there is great value, it is better to buy a return ticket. Even if you do not use it, you can sell it to another person!