"Antique calf" as Edward Green uses it comes from the tannery with random blotches of a darker shade applied to the leather. It is then the skill of the clicker (cutter) to align these blotches to the important part of the shoe. Once the shoe is completed, the last stage of production is the finish. The shoe gets treated with stains, creams and snake oils of every description to get that antique look. The finisher can accentuate the antique thing or he can calm it down. Have a look at this Japanese website and scroll down to "Finishing touches, Part Two" (particular the pair with one shoe unfinished and the other one finished): http://shoe-com-hp.hp.infoseek.co.jp/eg_tour02.htm
It is up to you to decide how much or how little antique look you prefer. The samples of bespoke shoes shown on site look absolutely exquisite and glowing: http://www.edwardgreen.co.uk/Events/index.htm
I'm sure you won't get anything less. But as you are paying, and a great deal at that, you can ask for some service. Let them prepare three samples of your chosen leather (not to small, 10"x10"), with light, medium and heavy antiquing and then make your choice. If you ask an interior decorator to paint an armoire, they would equally come up with colour-charts of the various finishes. Edward Green even offers bespoke shoes in bullfrog. How does that look like? But of course, should your bullfrog shoes squeak, they might well say: "Sir, that's the nature of the beast."