Quilted Petticoats Over Panniers?

I can't figure this out....

My assumption, based on a quote from Iris Brooke's book 'Dress and Undress' was that the quilted petticoat replaced hoops.

' Mrs Rook...is just come from France and is come without a hoop, and tells me that except in their high dress nobody wears one. Their sacs are made proportionally narrow and short, opened before with a petticoat and trimmed and with a stiff quilted petticoat under.' (p.83)

Meaning you either wore a quilted petticoat or you wore a hoop.

But my little world seems to be tumbling down and within the same book it seems.

One of my favourite drawings from her book is on p.82:

And until now I hadn't actually noticed that she seems to be wearing a quilted petticoat under her apparent apron. I don't know if you can see it from this scanned in image but there's definite etches of the repeated circular design associated with quilted petticoats. You can see it just as she lifts up her apron. 

But Iris doesn't often mention where she's sourced her information from and I don't just want to decide from a mere drawing that therefore they were worn over panniers.

So I did some hunting online but didn't come up with much.

Except I did find this image in the Manchester Art Gallery:

And I rang them and tried to find out about the outfit but the gentleman on the phone couldn't give me much info. He did say that the petticoat wasn't initially part of the outer dress ensemble and that they at the museum had put the two of them together and he did say that, as far as he was aware it was a normal quilted petticoat, one not cut differently or made with longer sides to accomodate the panniers. I asked him what made them put the two together but he didn't know the answer to that and said he couldn't give me anymore infomation as the outfit was on display and therefore not at liberty to be looked at.

'Pity' I said.

And that is that; at this precise moment.

If anyone out there has any other images or infomation, oh I'd be oh-so-grateful if you got in touch.