Maddy, could you clarify the 789/799 change? The GRO data says 789.
Not Maddy(!), but it is 799 in the original GRO birth index (see image)
And 789 in the new one

WHITWORTH, ELIZA ELLEN
Mother's Maiden Surname: AIKMAN
GRO Reference: 1889 S Quarter in SOUTH SHIELDS Volume 10A Page 789
Same for all the other entries on 10a 799 in that quarter
All are given as page 789 in the new index.
So the new index has two lots of births indexed as page 789, those who actually are on 789 and those originally on page 799 as well!
Human error I guess, but I don't remember seeing that before.