Shower Tiling- Tanking Required?

Hopefully this is a quick one, (I have searched)

I am using porcelain 600x300 (ish mm) tiles with Bal rapid set on the walls. I have a quadrant shower tray and the wall tiles within the shower area will be onto solid masonary walls, so do i need to tank this area? Bal WP-1 etc? Its just the evidence i have seen was only for plasterboard walls etc.

please help as i`m getting up to that area in a day or 2. (which means about a wekk with my tiling pace)

I am just using a thermostatic mixer off the boiler with one of those vertical cloudburst shower heads, so i`m not anticipating too much water on the walls (or behind them now i know water resistant grout actually lets water pass through it)

If you want to tank prior to tiling, then you should do all the walls, plaster board or otherwise. Water will damage any wall surface given time. We strip out plenty of old shower enclosures, so we get to see all types of water damage.

i take it thats a yes then.