Thankyou to everyone that responded, and my apologies for not replying sooner (exams & then moving house got in the way). I hope to catch up with the fellow that has grown this amazing specimen, and will let him know your thoughts. If I can get another photo to show the immensity of its growth, ...

I was visiting another cacti enthusiast the weekend before last, and in his yard is a huge cactus that he told me he doesn’t know the ID for. Location is in the Wide Bay region of Queensland (think Hervey Bay), in Australia. It was too big for me to get an above photo, and too large to fit the entir...