Thanks for the responses.
I have another relative buried in Manor Park. Via Deceased on Line, I was given the option to buy and view the Grave details and the 19 other burials in the same plot. It was simple to see that relative was in a Public Grave.
However, with Rose Eliza Payne, I have only the option to view her Burial Register entry - which I bought. There is no-one on the same page as her with the same grave number.
I know this does not mean she is in a private grave, but it is odd there are no other grave details...