How do i open side door of Van Transit 2004?

If it is a slam lock type (like the ones used on BT vans) I had to access the lock system from inside the van, presuming you can get in the back?? undo the mechanism from inside the door, and soak it in Meths for a while, then puttin the key in and wiggling it a lot.. till it turned, then replacing it in the door. probably hard to break in though, easier to access inner lock mechanism from inside.
G

Gem
April 2007