Very interesting Christine: but I wonder who did make it? Looks to have 10 flutes, so despite being 5mm thick glass it could still have been made by Chance if it's around 7" diameter. The 'bullseye' centre is rather curious but could have been formed after slumping, I suppose, if it wasn't part of the mould.
I've no information on whether Pilkies ever made slump glass, but it's not inconceivable.
Strange they were celebrating the 150th Anniversary on the 151st year! Maybe someone's slide rule had a slight bend in it, or perhaps they forgot! :lol:
I do have a Pilkies 150th Anniversary pin dish that was almost certainly sourced by Chance.
EDIT: Like this one :
270013131425