I assumed the problem was Siri however it was actually the Accessibility settings that was the problem.
Somehow the VoiceOver setting had been enabled. The solution was to tap each button once, wait for the VoiceOver description of the button to finish then double tap that key, that will then get past the Enter Passcode screen. Then navigate to settings, general, accessibility menu and disable VoiceOver. As mentioned by someone above you will need to use three fingers to scroll.
That sorted my problem out and I'm back to enjoying playing with Siri. Hope this helps