They can get it from the BBC itself, but only for one more day. Original broadcasts are archived on the BBC 5 website for one week. It should be available approximately until Thursday evening GMT.
I've seen a couple explanations how to listen to it direct from the BBC, and was finally able to get it to work now.
These are the instructions at www.hbuecker.net/london2.htm
"You just go to:
Then in the middle of the screen it says:
Listen again to Drive: Mon | Tue | Wed | Thu | Fri
You choose Thu, and then you get a pop-up window, and
(on my computer at least) it starts playing; then you
go to the time 02:14:15
If you lauch the show in Real Player, you just scroll
But on my PC it worked differently. What opened was the BBC Radio Player. It allows you to skip forward in 15 minute or 1 minute segments. It shows the playing time as from 16:00 to 18:55 (the show is on 4 to 7 pm weekdays).
Fast forward 4 quarter hours and you are at 15:00. The interview with Peter Power comes on about 15:01 or so.