Hey there! Try Life Reminders (link), I tried it and it may be the one you are looking for. Let me know if that's it. :)

Thanks for your suggestions.
What I was looking for was the sort of reminder that I had on my old stupid phone (ie pre smart phones). I'd enter a few words and a date and time and it would "ring me" until I answered it. I could then tell it to remind me again in 10 minutes or discard it completely.
So, Keep, Wunderlist, Todoist & Any.do don't 'ring me' to tell me when I need to do something. That are all just handy ways of keeping a To Do List.
And Remind me only send a little "Beep Beep" noise of one sort or another, not an insistent noise that keeps going until you 'answer' it.

So none of these even really fit my criteria.

Best Regards, Trevor

Hi there Trevor! Here are some reminder app that should work on your phone.
- Google Keep (link)
- Wunderlist (link)
- Remind Me (link)
- Todoist (link)
- Any.do (link)

Let me know which one you start using. :)