Yes it's Walnut, Parker-Hale got their stocks from the Italian company "Sile" so I would guess it's either Italian or Turkish in origin. P-H seemed to like the lighter honey coloured woods so this one is quite red. I guess it depended on what was available at the time at the right price.
For an 1100 this has good grain normally it was the Supreme , presentation or the M81 classic's that had this type of grain, or that's how I see it.
I am about to try the spray on Tru-Oil on another stock. I's a P-H 1200V that had the high gloss finish and well it was quite badly knocked about and chipped in places. So I stripped it and tried some yaht varnish
it was not a success as it went splotchy
so I have got to strip it again and thsi tiem I will try the spray on Tru-Oil high gloss to replicate the factory finish.