It has always worked so well on the iPhone I’ve forgotten how I did it.

For some reason my Gmail (custom domain) works instantly in the iPad, I’ve forgotten how I did that already!

But I am now setting up the Google (Custom Domain, apps docs, whatever they call it!! – How about Google Live? Google Cloud? Google Everywhere? To hard to name: Gapps?)

Short answer, worked instantly:

http://www.gilsmethod.com/how-to-add-google-calendar-to-your-ipad

Maybe this that I had already tried

http://www.google.com/calendar/hosted/psybernet.co.nz/iphoneselect

had a part to play.

Anyway it works

The MS Exchange way did not, however I had to get my Contacts working using MS exchange.