"Good point," I conceded, not daring to mention that on a recent overseas trip, I'd come across some sort of super-toilet, electronically armed with numerous bidet functions. Unfortunately, I was too apprehensive to press any of its buttons, in case something ghastly was sprayed over my exposed posterior.
"If you want to do your bit to help preserve the planet, you should seriously think about installing bidets," the tree-defender continued, clearly assuming such devices were beyond my comprehension.
In a last-ditch attempt to counterattack her credo, I responded by saying that because we live in the country, we have only a long-drop toilet, and short of diverting the garden hose into the inner sanctum, I was technically limited in what could be installed in the corrugated iron outhouse.
Her baleful stare confirmed to me that people who practise extreme beliefs, particularly on greenie matters, are not usually noted for their sense of humour.
"You don't expect me to believe that rubbish, do you?" she snapped, tapping her glass and clearly indicating she was bored with the conversation and wanted to seek more agreeable company.
"We all have our ways for caring for the planet and our philosophy is, what grows from the earth, should be returned to the earth," I piously suggested.
"Filling the countryside full of untreated toxic waste is hardly an exercise in good housekeeping in today's world," came the retort as she walked away.
Since she had raised the matter of toxic waste, I would have liked the opportunity to discuss the interesting parallel between such effluent and untreated cocktail party conversations, but she was already out of earshot.