This is a recipe I developed in the 60's and made large quantities for our restaurant in Portelet Bay, Jersey.
I used the same recipe for our restaurant here in Australia, 'Watney's' in Allora, Queensland.

WATNEY'S MAYONNAISE

Ingredients

1 T cornflour
1 cup warm water

1 egg
1 t dry mustard
1½ t salt
2 T sugar
3 T vinegar

¾ cup extra virgin olive oil

Procedure

1.     COMBINE CORNFLOUR AND WARM WATER.  COOK 1 MIN AND RESERVE.

2.     PLACE NEXT 5 INGREDIENTS IN BLENDER AND BLEND WELL.

3.     WITH BLENDER RUNNING, SLOWLY ADD THE ¾ CUP EXTRA VIRGIN OLIVE OIL.

4.      ADD RESERVED CORNFLOUR MIX AND COMBINE WELL

VARIATION -  Add to the basic recipe :-
3 T plain yoghurt and 2 t's gelatin and combine in blender.  This makes a creamier less acid mayonnaise