The Archers scriptwriters don't know how long it takes to grow a baby...

[WendyWeber]

...they appear to have had too many fingers to count on

Is this Hayley you're on about? The child behaviour on there is often wrong,too -- they talked about Phoebe eating books at 2.5 yo, etc.

Isn't Hayley now played by a different actress who has great difficulty maintaining a Brummie accent? Perhaps that could account for the extra long pregnancy.