Thanks, to each of you for your thoughts and ideas, I am taking note of them all.

Donna, I honestly don`t think there is anything wrong with Ebbs but there could be so I will certainly keep what you said in mind. And she tends to `dig to China` too sometimes and make a real mess! I will begin by putting both boxes side by side as you suggested and see how it goes. Thanks.

Johanna, of course you are right in that there could be more to her peeing outside the box than just accidents. I am sure it is not because of the tray being too dirty for her though, I am really fussy about keeping it clean, though it did make me think about this batch of litter, it has more powdery parts than usual...though, no, it couldn`t be that, the other time she peed outside it was a while ago when I was using the other batch.
No, she is not a big cat, she is small boned and quite dainty but I have an idea a deeper box might be better for her......
.....I just heard her scratching in her box and went to look and, yes, she peed inside ok but it did remind me of another odd thing she does. For a while the tray was close to the wall and when using it she would scratch the wall too, so one day I put an old heater next to the wall and moved her tray forward a bit, and guess what, she scratches at the heater front instead! I have no idea what that is all about!

kitten645, like I already said to Johanna, Ebbs isn`t a big cat so a covered one should be big enough for her, whether she will like it and use it or not is another matter!

Just been (well about ten minutes ago) and took a picture of her and her litter tray

though you can`t really tell the size of the tray she has now (she wouldn`t sit closer for me ) it might give you all some idea.

Kirsten, thanks and yes, I am aware that some cats just don`t like them, I just hope Ebbs does. Thanks for your input.