Is this illegal?

[PianoPants]

So I have a little trailer caravan that folds down to the trailer. The electrics aren't working so I've installed a trailer board and all the lights work. However, someone in a shop said that wouldn't be allowed and I might get stopped. But surely it's fine if the lights work? As you'll see in the photo, the new lights board is above the license plate.

In the dark/poor lighting such as fog, vehicles behind you wouldn’t be able to tell how wide your trailer is as the board & lights/reflectors are in the middle of the trailer rather that the edges so you may get pulled.

I don’t think that’s road legal, for the reasons @Totallyworthit said.

Does it still have reversing light and fog light?
As above, don’t be surprised if someone swipes the side of the trailer in the dark.

It isn't legal because the lights are too far from the edges of the trailer.

Lights are not far enough out. But the chances of the old bill pulling you for it are remote.
You can get wider boards or just replace the original lights.

Fuzzyduck is spot on
The regs are here just check as it has a drawing for light position and how far from the edge
www.legislation.gov.uk/uksi/1986/1078/contents/made
Personally I would just get a wider trailer board if you are concerned