Probably the last word on this subject, I have received an official reply from Ford Technical Information Centre who state...
“…..This concern is being investigated by all vehicle manufactures at present, not just Ford.
The concern is noted to occur in cold weather conditions. It is suspected to be caused by a differing bio fuel composition between different fuel manufactures. When the differing bio compositions are mixed in a tank, a reaction appears to be happening under cold weather conditions, forming a jelly like substance, which produces a restriction in the fuel filter.
However this is still being investigated & we are unable to provide a definitive answer. The above explanation is what we believe to be happening at this stage of the investigations. It has been confirmed however to be a fuel issue, rather than an engine of duel fuel system design concern.
I can also assure you that all vehicle manufactures appear to be reporting the same concern this winter, not just Ford…….”