Main Oven Won't Turn Off On Creda Cooker?

Had to replace the timer on a Creda 48345 as for some reason the main oven light, main oven fan, cooling fan & switch light remain on unless the cooker is switched off at the mains switch.

However this fault is still present now that the timer has been replaced (although the original timer had failed).Double checked the wiring to the timer and it's correct as the timer appears to work correctly.

How do I repair the cooker so that the main oven remains off when turned off on the fascia switch without having to turn it off at the mains switch all the time?