Location of alarm siren on 2012 Superb Elegance estate 3.6l V6 4x4

I have a 2012 Superb Elegance estate 3.6l V6 4x4 which I have owned from new. It has started setting off the alarm about 10 minutes after parking up. The alarm turns off ok. Vehicle battery was changed just under 2 years ago, seems fine. From my initial research I am leaning towards this being the backup battery in the alarm siren failing..?? It seems getting 12 years out of it is good going.

I am confident I can replace the battery myself, but I have no idea where the unit is. Does anyone know for sure the location on this particular model? I found a post somewhere for a 2011 Superb which said it is in the rear right corner (looking from front) of the engine bay next to the bonnet hinge, but in the photos they put up the bay looked completely different (obviously not the V6) and I cannot see anything in this area on mine, although I haven't stripped out the cover there yet. I know other Skoda models have it under the offside front wheel arch but I don't want to start stripping that out unless I KNOW it's there...

Cheers.