Filling LW TDCi Focus

[Matty4]

Tried to fill my wifes Focus today from a couple of plastic jerry cans of diesel I had in the garage. As the Focus doesn't have a fuel cap I tried to push in the plastic pourer spout on the jerry can into the filler but for the life of me could not get the little door to open and allow it in.

No matter how or what I tried the pourer was not going in.
Tried pushing down on the black plastic slider thing on the bottom of the filler neck with no result.
I finally gave in and drove it up to the local servo to fill it and the filler nozzle went in as per usual.

Has anyone successfully put fuel into one of these from a jerry can?

I know that if you ran out of fuel on the side of the road you'd be stuffed.