It was about 4-6 months ago. I commented on it in another place. [Rosie] Trains now run from Hammersmith and then effectively transfer from the H&C to the circle. I don't know what proportion do that and whether they can go round a few times and then escape out to Barking. It's been the subject of frantic discussions at CAMREC.
I think they run from Hammersmith to Edgware Road via the circle, then back the other way. I will be down in London (hopefully) later in the week, so I shall report back when I know more. I only realised when I looked at the tube map the other day.