Pam is a strange, inconsistent character in many ways, I think.
I mean, parents in many children's books are just background filler to be got out of the way so that the children can have risky adventures, but AF is a more serious novelist than that, though I think there's a bit of that trope sometimes going on with Pam in something like The Marlows and the Traitor, where they're all off on holidays at a hotel and then Pam goes off to see Geoff for the weekend and is lied to by the authorities about everything. (Is she ever told the truth, actually?)
There's somewhere she's described as 'gay and improvident', I think, and there's that blithe, irresponsible side of her that blows the Last Ditch on Catkin and Chocbar. Then at other points she's quite strict and doctrinaire about hunting manners or the children shouting at one another around the house, or the Changear affair or the fallout from swapping for the netball match and the Play, and we see her coming down hard on Ginty in her Patrick-obsessed moments, or lighting cigarettes in irritation at the breakfast table. She doesn't seem to have any particular input into whether Rowan takes on the farm manager role or not, and refuses to invoke any kind of parental authority over Karen when she's contemplating her disastrous marriage.
She eloped as a teenager because her mother wasn't keen on Geoff, but after an initial period of balls and parties (recalled in Mum's Chest), she's now essentially in many ways a single woman living alone, in a giant entailed house. She has staff, so doesn't do housework, her cooking is famously awful, all her children are either at sea or at boarding school, and she clearly has no involvement in the farm. No one even suggests she might step in when Mr Tranter has his stroke.
What does she do all day?
It must have been an incredible change when Rowan left school so was at home all the time, and then when Karen, Edwin and the children moved into the Tranters' house.