As far as I know the law is that it has to be 'checked regularly by a competent person'.
It's down to you how you interpret that.
I know lots of people who never bother with it
Nick...
As a holder of C & G Ag Machinery Technicians Certificate and a N. Dip. Agr. Eng. (Nowadays called a degree) I would suggest that I am competent.
Insurance Co. thinks otherwise -