how to wire up a 3 gang with two 2 way switches?

Try:
Brown from feed to COM, brown to bathroom to L1
Brown from other feed to L1, brown from 2 core and earth for hall to L2, 3 core to hall brown in L1, Black in COM and grey in L2, depending on how the other switch was wired
Do the porch switch the same as the other one in the circuit, probably brown to L1, Black to COM, grey to L2.

There are several ways to wire 2 way switches, but this is how I would do it.

Adam
August 2009

It is doubtful that anyone here can offer you any help that solves your problem and keeps you safe - you will be better placed and it will be much quicker to call a certificated tradesman.

Your switch plate will have three completely separate switches each with three terminals. The Com or common terminal of each switch connects to its respective L1 terminal when the switch rocker is in one position and to the corresponding L2 terminal when the rocker is in the other position. One of the switches will very probably be upside down with respect to the other two.

Stay safe and remember Lord Finchley...

Lord Finchley tried to mend the Electric Light
Himself. It struck him dead: And serve him right!
It is the business of the wealthy man
To give employment to the artisan.

Peccavi
August 2009