I have never heard that trick about a cup of water. makes sense though.
I carried CKPS in the truck for years incase I needed it. turns out i did.

 

Thanks all! I’m just about to purchase my CPS. do you think it’s fine to get one of the cheaper brands for £35 or should I stick to BOSCH (which is closer to £100) I only need to keep the car running for another couple of years before I sell…

 

The cheaper brands may not last a couple of years.

 

All depends on the heatshield. Factory heatshield wrapped in foil is easy option.