This model was originally designed by Bernard Perrier and was the subject of a Modelplan in issue 89 of Constructor Quarterly. There is another version of this model by Chris Fry as well.
The model is easy to construct, and it has a steering mechanism which can be seen in the second photo.
My model has been by shortened by one hole at the rear, relative to Chris Fry’s version. Due to this the rear plate holding the spare wheel has to fixed by blind nuts or threaded bosses. Mine has 2” HD tyres from David Taylor, which look right on this subject. I have also modified the mudguards, the steering track at the front, and the gearing for the steering. This is a cast pinion 26n, driving a plastic contrate 28p as the access is tricky.