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Edited sorry degs for calling you irish.
My guess is that he is going to be cutting through 4-5 inches on concrete. If you take a basic circular saw you can bind it in a piece of plywood. Also the max depth on most of your STANDARD circ saws if what 3.5" I believe. Those masonry blads for saws are made more for cutting durarock or cement board as some of you may call it NOT concrete. Its bullcrap that they say you can cut that. Plus if he hits rebar say goodbye to mr saw and crazy englishman!
A demo saw typically has a 10-12" blade and can cut through 5.5"+.
Demo saws are loud abnoxious and BAD ASS. A circ saw would take hours for him to cut anything. Demo saw done in 30 mins or less.
Now the only issue I see here is that you will have a crazy english guy with a saw and probably drinking. hUMMMM sounds like fun I AM IN!!!