On Fri, 29 Sep 2006 03:08:03 GMT, David of Broadway wrote:

Also, can two people share one Oyster travelcard so that if I had a
zones 1-4, himself could use it on the days I'm not going to work
from his place if he didn't fancy cycling to work (which is what
he usually does)

Yes.

No. Pity you chose to contradict Paul C., who posted an hour before
you, without any explanation. To quote from page 3 of TfL's "Get the
most out of your Oyster card" leaflet: "If you have a Travelcard/Bus
Pass on your Oyster card it is for your use only so you cannot let
someone else use it." However, "You can let a friend or someone else,
use your card, if you only use Oyster to pay as you go."

Why is this the policy, and is it enforceable?

I've often wondered how (or whether) they enforce it, as photocards
aren't required for Travelcards on Oyster.