In message .com, Rick
writes

I take it that there is no concept of a free bus-to-bus transfer in
London? At least I can't find anything about it on the web or the TfL
site.

No, but a one-day bus pass allows unlimited bus journeys throughout the
London area for an entire day and up to 4.30am the next morning. You can
buy one as a paper ticket (3.50 UKP), or you can use Oyster "pay as you
go", which will cap the daily cost to 3.00 UKP (i.e. twice the price of
a single cash fare, but allowing unlimited transfer).

Whatever happened to the Weekend Travelcard?

Not sure why it went, but a 1-day offpeak travelcard for use on a
Saturday or Sunday costs 4.90 UKP for Zones 1+2.

--
Paul Terry