I'm not trying to be a "cool grandad", really I'm not
If you have ever had to sue someone else and gone through the courts or Employment Tribunal, or if you have been asked to sign a compromise agreement upon the termination of your employment, it’s pretty likely that at some point the words “without prejudice” will have cropped up, followed (perhaps) by “subject to contract”. They can be baffling and many clients ask me what “without prejudice” means when I’m taking them through a compromise agreement. One client once asked me to write a letter to the other side “with prejudice”. Many people, lawyers and non-lawyers alike, write the words “without prejudice” on all their correspondence in the hope (presumably) that they will act as some kind of Harry Potteresque invisibility cloak to stop their words being thrown back at them in court. It doesn’t always work.