Because the 3600Br is double insulated it uses a two core cable so if it's just the mains plug that requires replacing it really doesn't matter which way the Blue and Brown are connected, but if you want to be pedantic then Brown is live and Blue is neutral.
If however you are replacing the mains cable, then as shown in the photo, the brown and red wires with eyelets go to the switch (missing in the photo) and Blue goes to the joiner. I hope that this helps.
