Then, try this, as I suggested earlier. Start by turning the supply off, at the mains.
'I wonder if (looking at your photo), the rightmost brown sleeved, is the neutral, and should be in the leftmost terminal(neutral), and the middle brown sleeved one, might be the switch wire, belongs in the rightmost terminal with the brown flex? But why did they mark the neutral with brown sleeve??'
Once you have swapped the wires as above, then turn the supply back on, with fingers crossed, hoping that it doesn't trip.
Lacking a meter, a good alternative, is a test lamp. Just a light bulb, in a lamp holder, wired with a flex. You have such a device, connected to that ceiling rose already!