Thanks for the thoughts and links folks
I think Pilgrim summed up pretty much what has been bubbling around in my head, all I would add is that during warmer periods the sea level must have risen and cut Britain off from the mainland several times, to be rejoined again in succeeding Ice Ages as the Guardian article suggests - "Prior to this ridge being breached, Britain would have been a promontory with a very clear connection to France, but once this happened every time there were high sea levels Britain became an island," The Guardian are talking about an event 400000 years ago with the second lake and breach 180000 years ago (about the same time as the BBC are suggesting – give or take 20000 years). If this on/off island situation continued after the second event as well then the diagram at the bottom of the BBC report showing the various ‘incursions’ of early man makes a lot more sense to me now.

Fitz – I’ll have a look at those reports but they look a bit heavy going in places, here’s a few random gems from one -
‘global eustatic component of sea level rise’, ‘glacioisostatic
rebound in the western Highlands’, ‘Shoreline uplift isobases (in metres Ordnance Datum (OD)) for Main Lateglacial Shoreline of Younger Dryas age’, ‘Rheological models and glacio-hydro-isostatic rebound models’

Do they do a pop-up book version ;-)

-Chris