Can I add a light to this junction?

[AP1990LTN]

Hi, is it possible to add a light on a separate switch to this junction box?

 

[Dartlec]

Hard to tell from just that picture...

You would need there to be a permanent live as well as a switched live to be able to add an additional separately switched light - and that junction box looks pretty much full already.

The wago connector with Live(brown) is a 3 way, and there should be 4 live connectors if it was all switched live, so there may be another one below it.

You'll probably need an electrician to look at it and test to confirm.

What does the flex coming out of the removed top of the junction box go to?

 

[littlespark]

I would assume this is just a switchwire and neutral feeding 2 x lights (?) with no permanent live.
I could be way wrong there.

You could get an electrician to replace the T box with an adaptable box maybe 100mm x 100mm to give more room for the joints.

You could add another switch and light, but if I am correct above, the new switch would only work if the first switch was on first.

There are solutions using remote switches and receivers such as quinetic.

 

[Spoon]

Even if you did have a permanent live feed in the T box it looks like there are no spare ways to take your cable out, so the best option is, as mentioned by @littlespark above, to replace the T box with an adaptable box.