Update: the VED reminder arrived inviting me to pay £145 for the period to 31 March 2021.
I went on line and paid.
I will not pay any more if they come back and ask.
I've also asked my MP, John Glenn (one of the Treasury Junior Ministers) for clarification.
I don't think they apply a retrospection when you've paid that year Peter. The new rate will only apply from the date it becomes law.