Hey Graeme,
A very nice capture of this tidal flat.
When I was in the UK, almost 20 years ago now, I had rented a car and was parked along a roadway that crossed a tidal flat to one of the small islands. I was taking photos of the incoming tide, and how it was covering the road in front of me and didn't notice that the water was also starting to cover the road behind me. The water was starting to come over the road and was probably about a couple of inches deep around my car. After being alerted by some others around, I ran back to the car, tossed my gear into it and backed off the road and parked in some safer higher ground in a parking area on the mainland.
That sure had my heart racing, thinking that I was literally seconds away from the car being covered by the sea.
Here in the US, most of our beaches our tides moves in or out about 30 feet or so. There are some flatter ones where maybe the tidal movement is a couple of hundred feet. But I don't know of any where the tidal change literally seems to be a 1 mile like in most of the UK. It's crazy!