That's right Dominik and Alexander had spotted something very similar to Brian the Sewer Vent, but in a slightly smaller form factor.
Obviously I couldn't let it go and had to ask on the official 40k page and the Warhammer Community team were their usual awesome selves, joining in with the fun and alluding to a direct lineage to my favorite terrain piece.
And then I had it proper confirmed from Nick Bayton [who kindly engineered my meeting with Brian in June] that Brian's Father - Dave Andrews had spawned a second sewer vent specifically because of my love of this terrain piece!
I'm not sure how to process that to be honest exceptto be absolutely over thre moon with delight that my persistence has brought this mini version to the hobby community. I can only hope the next thing on Dave's hobby table is a replica scale version that will connect with all the industrial terrain sets ;) I'm like Andy Dufresne in Shawsank...