Change default invitation account for iOS Calendar

I have two GMail accounts on my iphone ... my personal GMail and my Work Google account. My work account is the default account for new calendar entries. When I send an invitation from my iOS device (iPhone or iPad), the invites appear on my work calendar, but the invitations are always sent from my personal account. This reveals my personal GMail email address to all my work contacts, and it also means that when someone responds to the calendar invites, they are directed to my personal account.

I cannot figure out how to change this. TO BE CLEAR ... my default calendar in settings is my work calendar and events are, by default, getting set up on my work calendar. Its just that the email "from" address on work-calendar invitations comes from my GMail address.

NOTE that this behavior also appears to be happening when using iCal on my Mac.

THANKS.

- David