Thank you @Peter Steiwer" href="https://javascript:" title="Copy to clipboard">@Peter Steiwer that nailed it swizzling .found. 

Thanks for the advice @Vitaly Furman, I used  square bracket syntax as I was iterating over an array.

I did try my code using {} brackets and my code still isn't ending the nested IF loops upon finding the field and value that match.

Regards

Stuart

Source JSON:

{
  "patient": [
    {
      "age": 51,
      "name": {
        "forename": "Bill",
        "surname": "Brighthouse"
      }
    },
    {
      "age": 2,
      "name": {
        "forename": "Dickie",
        "surname": "Bird"
      }
    }
  ]
}