Hi Clive,
interesting phenomenon! I think it is Barrow.
- I calibrated your photo into Jim Mosher's Lunar Terminator Visualization Tool (assuming the time of shooting 10th July 2008 at 04.00 UT, colongitude being 353.917). Labelled some features there.
TAL 250K*Celestron C8-N*SkyWatcher Skymax 150 Pro*TAL1(Mizar)*EQ6 Pro SynScan*Celestron Advanced GT (CG-5 GOTO)*Baader Hyperion Clickstop Zoom 8-24*17 mm UWA-70*TeleVue BIG 2x Barlow*Celestron 2x Barlow Ultima SV Series