Thanks but I think either Tyne or Humber could be swapped with Thames so there is not a unique solution. Good try though.

Good for those who dig their UK geography, but maybe one to miss for those whom the subject is a massive blind spot. I personally prefer my grids to cover a variety of topics, but I'm aware there are plenty of people who feel differently.

Toast that is the whole idea that there are 'crossover' answers for the different groups of 4

Bob this has been discussed before. Crossovers are great but only one solution that covers the grid is permissible. On this grid there are three equally valid solutions but two of them are marked incorrect.

Toast is correct. The solution has to be unique. This is not unique as Toast describes. It should not discourage anyone from creating a grid but can be a learning point for creating any future grids. Everyone can be fallible - it is difficult to get everything spot on.

I enjoyed it. Not too difficult, but interesting.

not too difficult

Humber is NOT a river. It is an estuary.