If I had one whole egg (my understanding being that the white has more 'setting power' than the yolk), how much milk would I be able to set?  If I tried to set 2 cups of milk with 1 egg, can I expect something like a creme anglaise or something thicker? 
My understanding (from school days, Mrs Crabtree would be surprised) is that 1 medium egg will set 1/4 pint UK.  That's 5 fl oz UK.  USA is different and metric different again.    I use 1 FRESH medium egg to set 150mls of milk. 