Driveway construction - membrane under or over type 1 and then gravel on top?

I presume that you mean the geotextile? ; This must go under the type one stone. It is a material that adds strength to the road and will prevent the stone of the type one being pushed down into the formation (the compacted clay etc sub soil under the top soil that you've removed). The type one should end up so well compacted that there is no chance of the gravel being forced into it. Don't forget : don't put more than 40 or 50mm of shingle. cm