Fleeping heck, I've never heard of rats in the soil pipe! That's scary. Well, the alternative to the flexible one I've tried was the 20mm offset connected to the short Mcalpine connector as in photos.
The rigit connector though it tends to slip out of the back of the toilet and did not feel very safe about it unless I put a piece of wood behind to keep it in place but it could also be the silicone spray I used on the rubber seal to make it slip in easier...
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