Good Find! I still get Paul McCartney news alerts everyday.I have noticed over the years he sems to be wearing the LCD Black band watch more often than caught wearing his Synchronar.I have seen similar close ups like you have posted but never seen these photos. I would wager it is a Solar aided/powered Shock resistant LCD.
He is a notorious vegetarian and dislikes any unnecessary waste such as batteries going into land fills.He also is into a classic original thing especially if it is meant and built to conserve and recycle power and tell good time.IMO