testing cables in a ceiling rose?

hi there my girlfriend has decided to change a ceiling rose for A new one... switched off the circuit at the breaker, god girl, then un screwed all the cables, yes you guessed it, she never labeled where they came from... so putting back the new rose was difficult... the cables that are available are 1 red,3 black, 3 earth.. i established the switchline as i brought a tester... placed on probe on the earth terminal and the other on the red cable... when i switch the switch on the buzzer came on, when switched off, the buzzer stopped... that how i discovered it maybe the switchline, hence the circuit is switched off at the comsumer unit when carryout this test... how will i noe establish the feed in and feed out, and neutral