English teams won 3 UEFA cups, 3 European Cups and 2 cup winners cup in the 70s. Scottish teams won 1 Cup winners cup between them. I don't think that argument would be very successful.
But.......Jock Stein led a team(all born within 20 miles of Celtic Park)to the first British win in the European Champions Cup and got no recognition, 12 months later Man Yoo won it and their manager subsequently was awarded a knighthood. Ok that was in 67.
Who cares though? Celtic are about as anti establishment as fan bases get (Liverpool not far behind) in Britain. They hate the government and the British monarchy, it's a bit peculiar if they get offended that they don't get any recognition from the monarchy despite consistently chanting against Britain.
The recognition doesn't come from the monarchy, the government recommend/nominate those given the honours, Thatcher's government(the establishment)were anti-Liverpool and there lies the reason Paisley was never knighted. Tbh knighthood's are not worth a carrot these days anyway.