OK so it turns out my Lounge P1 didn't renew it's DHCP properly when I turned it off and on and so didn't pick-up the Gateway change I made recently. So it wasn't talking to the network.
Now what I didn't realise was that this would mean it would try and record to the other device even though it doesn't really have a hard drive.
So this time round it was my bad... oops

I apologised to my BW already for swearing at it and threatening it with the remote.