Could you double check the number? I don't think there was 400, there's a 401, 403, 404, 411. There's a straight stitcher in this line too, but I can't remember which number it has (404 probably). They are all similar enough for me to say they are well worth money and effort to fix them up, all metal, gear driven, I am interested enough my self to get one :- )
I don't think all of them were made in the UK, I think the 411g was made in Germany only.