I carried Dexter down to the actual sea, which he loved. We sat him on the infamous Brighton pebbles (he's not been on the beach since he was a tiny baby). He didn't really quite know what to do with this unfamiliar surface and so resorted to default mode and put some pebbles in his mouth.
A slightly panicky and frenzied moment later, I had extracted the offending items from Dexter's jaws. For a while afterwards, I had to push from my mind the list of colourful characters/dogs who frequent Brighton's 'welcome to all' beaches. I'm sure it's good for the immune system.