I've converted mine. Well sort of. I have made up a hook up cable with UK camping plug (16A round pin) on one end and the US plug on the other to go straight into original socket on van.
Next step was to test this, so I used a us to uk travel adaptor and plugged a small flat screen tv into the wall socket in the van. It worked fine so I knew the plug combo and original socket was working fine.
Then I decided I didn't want to mess around with adaptor a so using the original socket mount as a template I made a plastic housing for a two gang uk socket and wired it up. You just have to read up on which wire is which in American wiring to make sure you get all of the in the proper place.
What I have left out is the built in trip switch in the original, I considered using it in my conversion but then I thought that most hook up points have trip switches in them anyway. I looked for something similar to include in my conversion but with the two gang socket there wasn't much room anyway so I'll just rely in the campsite trip. I'll post a pic but the van is full of stuff at present.