On first glance, this Les Paul standard looks like a bargain at £300, so if someone jumps in quick to snap it up, they'll probaby think they've pulled a fast one and have been able to take advantage of the seller's ignorance of the value.
https://www.gumtree.com/p/guitar-instrument/gibson-les-paul-guitar/1478624071
However the are several honking great red flags indicating that it is indeed the seller who is trying to pull a fast one
Its a two second job on Google to discover a Gibson Les Paul Standard is worth a lot more than £300
The truss rod cover is wrong - the printing looks like crap and it has no white edge
The Rhythm / Treble 'pokerchip' stamping is wrong
The switch has a hex nut rather than a knurled nut
The Strap buttons are shaped like fender strap buttons rather than gibson buttons
The back plate shape is wrong
The neck heel and cutaway shapes are not quite right
A Les Paul standard would have a decent hard case. This doesn't have a case
The tuner tips are a weird murky grey green colour
No Fret nibs
The fingerboard position trapezoid markers are the wrong shape, being too curved at the sides
The Serial number and 'Made in USA' stamp are marked with characters that are too thin
The "Guitar has been in the wardrobe for a long time, used to belong to my stepfather. I don’t play and know nothing about guitars, having a clear out and need it gone." story gives plausible denyability if challenged
Cash only — no tracability
etc...