Thank you, Mark and Elizabeth for your views. I need to take the editor’s advice seriously but I’m in the camp that mixing first and third voices adds confusion. As I said, none of the other readers gave a hoot, and it doesn’t sound like you two seem to think it is a particular flaw in and of itself. So, while I can use the other hints to improve the prose, the major edit will be in reducing the ‘I, I, I’ syndrome he felt was overdone. After all, every character is first person so it is a challenge hard to remove references to ‘I’.
I (sic!) had reduced it but I guess I’ll have to go at it again to do more.
If other contributors have different views then I’d be pleased to hear them, or whether to confirm those already given.