Worth checking through tickets though. For journeys in the NSE area often a through ticket is only around £2 more so better value than using Oyster, and there is one operator where the through Advances are actually cheaper than the ticket to/from London Terminals.The reality is that using PAYG for your local London bit is usually cheaper than buying a through ticket, especially if the tube is involved. For example, if I pick a few places in all directions around Central London within the Oyster area and compare the same Advance price level (the below use ticket code BUS as an example):
If you use Advances, they also give you protection in the case of delays on the local leg.