I just thought I'd give some feedback - Ria P was absolutely right, Baldrick seems to do this when he's tired after a good run around bless him!
I had him out and running and climbing all over me for about 40 minutes this evening and sure as anything as soon as I put him back in his cage he flopped down flat on his tummy in the exact same spot.
He's a funny little guy and I'm very happy to be his human 'dad'