Hi,
Further to my original post, the problem went away. Now, over a year on, and the problem has come back.
I have a NEFF 1461 Fan Oven and the timer is starting to beep again in an usual pattern. It seems to beep as follows:
1 beep, 4 beeps, 2, 2, 4, 2, 2, 4, 1, 2, 3, 4, 4, 2, 4, 3...