Having said all that, like you, I have definitely seen a more general issue of losing the index value in the past and I suspect your first suggestion would have worked in that case so thank you for taking the time to suggest it.

There is one other possibility - do not bind the new index property, but assign it. So, do this:

MyTextField {
  property int row: -1
  Component.onCompleted: row = index
}

Since you are adding itermediate property in Loader, you can actually do it there, when sourceComponent is changed.

This way the row is assigned only once. Even if index changes to -1, row will not be updated - so it should work as you intend it to.

One detail which I unfortunately omitted was that, because I have different types of property in my table and it needs to be initialised dynamically from data, I am using a Loader as a 'delegate factory' . The delegates themselves are defined as Components such as:

    // delegate for integer type property
    Component {
        id: intFieldDelegate
        MyTextField {
            validator: IntValidator{}
        }
    }

One consequence of this is that I don't have direct access to index etc in my delegate and have to introduce an intermediate property, index_ say, in my Loader (this is described at the end of the Detailed Description for Loader in the Qt documentation).

I have tried introducing a readonly property, as suggested, at various levels - in the Loader, in the Component instantiation above, in the implementation file for MyTextField but all with the same result.

YourDelegate {
  readonly property int row: index
}

And use this in your onEditingFinished handler. It should contain the original value from when the delegate was created.