The mayor's man duly arrived just after we had sat down to lunch and told me what I had long suspected was the case: we were not connected to the mains drainage. We were back to square one.
I recalled that Sue's husband was a plumber, although he worked away from home most of the time. But one Saturday while I was there, Alan came across to see if he could work out just what our problem was. Or rather, what was the cause of our problem. Alan took a long look at the system, first with the tank cover on, then again after the cover had been removed.
"It's your vent," he announced. "It's too small. The vent should be at least as wide as the pipe flowing into the tank, but it's not. And the top of the vent pipe should be much higher than it is or the gas will easily spill downwards into the courtyard instead of being cleared by the wind."
Alan offered to install a new vent, digging a trench from the tank to the side of the house so that the new vent could be fixed there and could release the gas at a much higher level. And so the work was done, although we discovered later that it was actually Sue who did the hard bit - digging the trench.
And that did solve the problem of the smell - although It did lead to another couple of small jobs for Chris and I a few months later.
~~~~~The River Loire again, this time at Ancenis.