Incorrect Photo Sorting

a) When I load photos taken on my iPhone into Photos, they will appear out of sequence from photos loaded from my camera, e.g an iPhoto shot taken at 1200 hours may appear after one taken on my camera at 1500hrs on the same day

Where are the photos appearing out of sequence? In the "All Photos" album? That is to be expected - that album will be sorted by the date you have imported the photos.

In any other album you should be able to sort the photos by the capture date. Ctrl-click the album or smart album and use the command "Sort > Keep sorted by > Oldest/Newest first":

The Moments should be sorted by the capture date automatically. If they are sorted incorrectly, check the date and time settings in your camera, if the settings are the same. If not, use the command "Image > Adjust Date &Time" to correct the time settings for the photos that are sorted incorrectlly.

It might be a timezone problem. If you took the photos in a different timezone than you imported them to your computer, the Photos.app will use the timezone of the current system time for the photos you import. hat can shift the time a few hours.

If the dates&times for the photos taken with one camera need adjusting, you can collect them in a smart album with the rule: Camera model is ...

I have one specific 'Moment' which has 2 days in it and can't be separated

did you ever quit Photos after you adjusted the times of the Photos?

That will force Photos to write the changes to the Photos library.

I noticed that it sometimes needs a restart of photos for the photos to move to the correct moments.

If quitting and relaunching Photos does not help, make a current backup of your Photos library and repair the library.

See: https://help.apple.com/photos/mac/1.0/?lang=en#/pht6be18f93

If you experience problems with photos in a library, Photos can try to repair it. If problems persist, you can also restore your library from a Time Machine backup.

Important: You should back up your photo library before repairing your library.

• If Photos is open, choose Photos > Quit Photos.
• Press Option-Command and double-click the Photos icon in the Applications folder (or click the Photos icon in the Dock).The Repair Library window opens.
• Click Repair to rebuild your photo library.

if you are using iCloud Photo Library, repairing the library will cause all photos to be uploaded and compared to iCloud again, and that will take as long as the initial upload. Don't repair, unless yu have checked , that all dates and times are correct.

Some of these shots were first loaded onto my iPad and subsequently uploaded to the MacBook.

Would that be causing the problem?

That should only be a problem, if you were no longer in the timezone the photos have been taken, when you imported the photos from the iPad. Then the photos will be shifted by the timezone offset to your current timezone.

And another problem I am frequently seeing when importing from the iPad or iPhone are videos. The videos are accompanied by a keyframe photo the will show among the regular photos, but usually incorrectly sorted. This is probably caused by the fact, that the videos do not have a capture date embedded, and the keyframe photos will download with the file creation date as the date, and not the EXIF capture date.

You may want to check, if the problematic iPad photos could be the keyframes of videos you took with the iPad or your camera.

Did you use the camera connection kit to download the photos to the iPad?

You're welcome.