Running a plug in cable behind a wall?

Hi there,
I wonder of one of the electricians could comment on whether it is allowable to run a power, cable, terminated with a plug through a wall?

Context is, a 13amp socket near ground level, and a projector on a shelf about one metre above, and amp about 0.5 metre up, so that both cables would enter the wall near the socket, and exit behind the projector and amp.

If not ok, is there an allowable way to do this?

Thanks in advance.

allowable but might look naff. if it is a stud wall could you consider using a flush box and brush plates top and bottom

Thanks very much Sureitsoff. I couldn't think of any reason why it would be illegal, but I saw from some websites that its illegal in the USA, so thought it best to check if it was legal here.

The cable will be coming through right behind the units which will be flush to the wall, so not visible, but the brush plate is a great tip for where they will enter near the socket, so thanks for that too!