It includes this note:
"Do I have to have a meter?
Yes, where technically possible. The Secretary of State for the Environment has approved our plan to meter customers' properties because we are operating in an area designated as being under severe water stress."
In this case, as the place is subject to limited occupation, say about one week per month on average, having metering may well be advantageous, and I have the option of remaining on the old payment system for up to two years.