In this case one half of the client couple wants a round pond, the other half wants a rectangular pond. We all wish to avoid marital strife and discord so the garden designer, showing the wisdom of Solomon (but less threatening), steps in with a diplomatic solution.
Thus we end up with both: a pond that forms a long rill with a central circle. A little like the London Underground sign but prettier. The central circle also forms a handy, deckchair sized island upon which to sit surrounded by planting – which is, after all, the best place to sit in any garden.
There are long borders along each side and a screen of pleached hornbeam at the end of the garden to give a bit of privacy from the neighbours. I did find that the client had put a gnome sized concrete replica of Charlie Dimmock in the border but the less said about that the better.