T&E to outdoors - seeking advice

Looking for advice on improving what looks like a bodge (not mine). A friend has a shop and paid a "professional" to install an illuminated sign outside - some time ago I believe. When in the shop the other day, he asked if I could make the cable run inside tidier (I'm electrically trained and qualified, but NOT an electrician).

The t&e cable from the sign runs inside a short plastic conduit to the bottom of a wooden window frame, where it enters the shop through a hole drilled through the frame. It is then run over the window sill (against the wall) clipped into place and dangles down to near the floor with a 13A plug on the end of the t&e which can be plugged into a nearby 13A outlet.

I suspect the installer has done this in an attempt to get around building regs on the basis that it isn't a fixed installation. But it looks like a bodge and it's really untidy (as well as potentially unsafe). My friend has tried to get a couple of electricians to make it better, but they understandably declined. I think my friend wants it hard wired in which I'm not happy to do, given I don't know how good or bad the outdoor work is, but looking at the quality of the work indoors, I have my doubts. I wondered about terminating the t$e just inside the window in a junction box, then running a neater length of white flex to the 13A plug. Or would you advice not touching it with the proverbial? (Scottish building regs btw ...)

No he didn't. Well maybe he paid someone but they obviously weren't competent. T & E should not be terminated in a 13A plug- the repeated flexing caused by plugging/unplugging will fracture one or more cores.
Your JB plan will work, the better way would be to fit an FCU next to the socket and terminate the T & E in that. But unless you have some documented qualifications and PLI I'd stay well away from the job- tell your 'friend' how to do it and watch him do it but leave him carrying the liability.
I suspect there's either more to this than you're telling or the electricians your friend has consulted are as fictional as the qualifications of the 'professional' who fitted the thing in the firsst place.

There's no more to the story that I'm aware of and I've no cause to think I'm being lied to. However, I take your advice on not touching it on the basis that although I have documented qualifications, I have no PLI and this is in a shop with the power run outside to the street. Friend has no practical skills, so telling/showing them what to do is a non starter. They'll just have to find an electrician willing to do the job. I've already pointed out that having a 13A plug on t&e is a bad idea.

If the plug is being unplugged every day than I can see it being a bad thing, but if it's rarely unplugged I don't really see it as a massive problem. Nearly all our wiring accessories are designed so that any work on them requires bending the wires in and out of the box and noone seems bothered about that.

What type of protection has the circuit got? Any RCD? Why not remove the T&E completely and replace it with White Flex all the way to the light and put a plug on the end of it? It's effectively then a plug in light still.

plugwash - very fair point.
chivers67 - didn't check what protection there is but the shop was fitted out in the past ten years so I'd expect there to be RCDs - but I'll check. Good idea on replacing the whole run with flex. I'll give that some thought.