The event suffers from the fact that HSCC run the track action, but individual organisers are responsible for their grids and entry lists. I would guess this is frustrating for the HSCC, and can also lead to the pre printed programme not being totally accurate....
There is now a problem with the circuit licence! It could mean some races using the historic layout and some the modern. No doubt all will be revealed, and hopefully drivers will know before venturing out.