Probably best not to go there.
HMRC are in the process of closing these loopholes off fast - and seem to be making noises that they will retrospectively claw back lost revenue. There are various schemes, mostly designed for people buying houses in the top bracket of SDLT.
An earlier one (now closed off) involved arrangements set up to satisfy Sharia law whereby the sales transaction was done in two staggered payments (one small, one large) and involved transfer of the property to a third-party company who then 'assigned' the property to the end buyer without further liability to SDLT. Because the first of two staggered payments was small and SDLT was assessed on it alone, the total SDLT payable was small. I gather many purchasers were not Muslims.
There's another scheme used by developers of existing properties as luxury flats whereby the developer buys the delirect property as a company, pays SDLT, but then adds a whole lot of extra value during the conversion process. When the end product is sold to wealthy customers, they actually buy shares in the company owning the property, and hence it is share transaction and not a property transaction (on which SDLT would have been paid).
I suspect that if one is wealthy enough to want to use similar types of schemes one knows who to ask without resorting to AB.