Add field to BO manual order entry form.tpl

[FAS]

Having problems getting an additional field added to the database in BO manual order.

I have added this code to /adminxxxxxxx/themes/default/template/controllers/orders/form.tpl

                <div class="form-group">
                    <label class="control-label col-lg-3" for="handbook_number">{l s='Handbook Number' d='Admin.Orderscustomers.Feature'}</label>
                    <div class="col-lg-9">
                        <input class="form-control" type="text" name="handbook_number" id="handbook_number" />
                    </div>
                </div>

And I have something similar working in order edit which works fine, but I can't get the database to update/add the handbook_number when entered in the manual order section of the back office.

I suspect it is to do with the javascript contained within the form.tpl, but I am seriously struggling with this one.

The handbook_number field is contained within the ps_order_detail table and, as I say it works fine in BO edit order.

The PrestaShop version is 1.6.1.17.

Any help please.