wrote:

During my former visits I bought some kind of London Visitor pass for
unlimited tube/bus travel.

It looks like that card is replaced by an Oyster card?


Not unless you plan to be in London for 7 days or more.

Can someone tell me how this works for tourists now?


http://tube.tfl.gov.uk/content/faq/t...troduction.asp

should more than answer your questions.

And what about the changes to the zone system? Last time there were 3
zones, there are more now...

Actually, there were and are 6 Underground zones.

What zone is Kensington (Hotel area)

Zone 1

and Heathrow (point of arrival).

Zone 6.

Most tourists will find Zone 1 single day travel cards sufficient, with one off
tickets for trips to and from Heathrow, but you may wish to think twice about
using the Tube from Heathrow. The Terminal 4 station is closed right now and
dragging luggage around on the Tube is difficult at best. Consider taking the
hotel bus or the train to Paddington.