Hi MIK
Thanks for trying to help. We now have 4 families that need this information and we are trying to work together.
We know he wasn't married in East/West Raynham, Neither did he marry in Mildenhall. So presumably somewhere in between, but this is a lot of parishes to cover, all the children were born in Mildenhall as far as we know. We have searched all Norfolk parishes but cannot come up with a likely marriage.
Your point about his wife's birthplace on the census... she died in 1803 so nothing to be found there.
One option might be records showing him leaving or entering a parish ie poor law, if anyone has access to such things.
Any more help would be gratefully received by all of us. Thanks