About 25 years ago I was contacted by the branch manager of a large national retailer about the company car the business was providing him with. He told me in great detail what expenses the company would pay and that the car would be bought by the company and owned by the company. We discussed the Fringe Benefits Tax (FBT) considerations and implication as well as compliance obligations.
I was on my going out to a meeting and just quickly scribbled the details on an A5 notepad ensuring that it met the requirements of a contemporaneous note as is my habit. In those days we still maintained paper correspondence files, so I ripped the note off the pad ripping the edge skew and put it in the "filing tray" (remember those?)
Over a year later I received a call from one of the Directors of the company, who let me know that the business manager had left and was suing the company for unfair dismissal. In addition, he claimed that the company car provided to him was promised to him and was therefore owed to him. None of the directors could remember the details and asked if we could possibly assist. I looked for the correspondence file and found the scrap of paper that I had written on and where it had been pasted onto an A4 sheet of paper and filed for posterity. This document was used as the basis of my affidavit to confirm what the manager had said, which resulted in the case being dismissed as it contradicted the case the manager was putting forward.
For this reason, it is the policy in our office to record everything (or as much as possible) in writing and we say - If it is not in writing, it did not happen. These days we use electronic record-keeping and note-making in 99% of cases.