Still runs the river

What a brilliant sunny day. Was down by the Clyde and there were people swimming in the sea from Largs right past Seamill and Ardrossan at every sandy spot. A bit like the long hot summer of '66 - or was it '67 - when I was in the water myself.
On the way back home, stopped at the Laigh Milton Viaduct near the village of Gatehead in Ayrshire. It was a haven of tranquility, there were ducks in the water and the river was absolutely still.
I liked the way the trees reflected in the water and the bright blue sky. Now how long will it last?