I have always understood that "hose in Hose" referred to flowers that had
one flower growing from the centre of another, most commonly Primula wanda
"Hose in Hose", Mimulus naiandinus "Hose in hose".
The plant finder list 5 nurseries with the primula, unfortunately I lost
mine 3 or 4 years ago, and I think I lost my mimulus this last summer
through neglect.
Oxslip was always said to be a cross between primrose and cowslip, though
P.elatior was supposed to be the "true" oxslip.
In passing.my "Bible" (probably printed around 1920) says
"The double flowered Primroses,white, yellow, mauve, red. etc, etc. are
"Antiques" of exceptional charm, whilst other interesting old Primroses are
Jack in the green, Gallgaskins, Hose in Hose etc".
I can find no other ref. to Gallgaskins.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk