Hi, this is when you need to be a 'Sherlock Holmes'
probably the other circuit cables, (3 Reds & 3 earths) are tucked up in ceiling.
what you have is 2 neutrals which go to blue flex end of rose + 1 switched live which would have been on its own & should go to brown flex end of rose, this should have red sleeve/tape on it.
It may be possible by examination to see 2 that have been twisted together or 1 that was on its own, if not and as has been suggested visual check not possible then continuity test from switch to each in turn will show switch line,
Always work on dead circuit and if unsure please get help, it should take no more than 1/2 hr for leckie to fix.