Wooley and Wallis's Wonky Slab from Whiteparish

Wonky auctioneer's photo (left)
attempted rectification (right)

A lump of stone described by auctioneer Woolley and Wallis as a "Roman slab" is being sold off (Rob Picheta, A Roman slab was found in a garden in England. How it got there is a 'complete mystery' CNN 5th January 2021). It is suggested by the sellers that this is yet another Grand Tour artefact that's ended up in the fields (in actual fact a bungalow garden)

The intricate (sic) slab features a Greek inscription that gives a clue to its origins, and has been dated back to the second century AD. [...] The slab was stumbled upon 20 years ago by the owner of a house in Whiteparish, a village in southern England, who found it in the rockery of her garden [...] the home's more recent owner took it to an archaeologist, who dated it to the second century with likely origins in Greece or Anatolia. Its inscription reads: "The people (and) the Young Men (honor) Demetrios (son) of Metrodoros (the son) of Leukios." The slab is set to be sold in February by Woolley and Wallis, with a pre-sale estimate of up to £15,000 ($20,300). Auctioneers are asking [...] whether anyone involved in the construction of the bungalow, built on Common Road in Whiteparish in the mid-1960s, might "recall the origins of some of the rubble used."

But I think there are some more searching questions about the object itself that need to be answered by the auctioneers' unnamed "experts". The front face of the top of the slab has a rusticated surface, and apparently was intended to be covered by another piece - like for example if this were the tread of a flight of steps. So why is the inscription below it? Why is the slab not the other way up, with the rusticated surface set into something else and the inscribed face of the slab exposed? Somebody else can explain why the form of the inscription makes it specifically "second century", I'd like to know why they are so certain it is ancient at all. Why does the auctioneer publish a photo that is slanted on the page (left)? What does it look like properly orientated (right)? None of the corners is a right angle, the two inscriptions in the wreaths are at different heights, the main inscription is neither parallel or perpendicular to any of the sides. 

Has the inscription been added to a reused piece of masonry, and if so, when and where? It would be helpful if in the description of the object, there was actually an identification of the source of the stone (you can do it, you know?). They say it is "marble" but in the photos it does not look like marble to me, just plain limestone. In order to assess what we've got here, it would also be useful to show the back... or p[erhaps that's the reason auctioneers so rarely show the backs.        

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